Release 1.0.128

Enable 128-bit integers on emscripten post Rust 1.40

.github/workflows/ci.yml

@@ -23,25 +23,22 @@ jobs:
       - run: cd test_suite && cargo test --features unstable -- --skip ui --exact
 
   stable:
-    name: Rust stable
+    name: Rust ${{matrix.rust}}
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        rust: [stable, beta]
     steps:
       - uses: actions/checkout@v2
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{matrix.rust}}
       - run: cd serde && cargo build --features rc
       - run: cd serde && cargo build --no-default-features
       - run: cd serde_test && cargo build
       - run: cd serde_test && cargo test --features serde/derive,serde/rc
 
-  beta:
-    name: Rust beta
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: dtolnay/rust-toolchain@beta
-      - run: cd serde && cargo build --features rc
-      - run: cd test_suite && cargo test
-
   nightly:
     name: Rust nightly ${{matrix.os == 'windows' && '(windows)' || ''}}
     runs-on: ${{matrix.os}}-latest
@@ -115,6 +112,8 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: dtolnay/rust-toolchain@1.31.0
+      - run: cd serde && cargo check --no-default-features
+      - run: cd serde && cargo check
       - run: cd serde_derive && cargo check
 
   alloc:
@@ -158,6 +157,7 @@ jobs:
         # https://github.com/rust-lang/rust-clippy/issues/5356
       - run: cd serde && cargo clippy --features rc,unstable -- -D clippy::all -A clippy::redundant_field_names
       - run: cd serde_derive && cargo clippy -- -D clippy::all
+      - run: cd serde_derive_internals && cargo clippy -- -D clippy::all
       - run: cd serde_test && cargo clippy -- -D clippy::all -A clippy::redundant_field_names
       - run: cd test_suite && cargo clippy --tests --features unstable -- -D clippy::all -A clippy::redundant_field_names
       - run: cd test_suite/no_std && cargo clippy -- -D clippy::all -A clippy::redundant_field_names

CONTRIBUTING.md

@@ -31,25 +31,19 @@ tests for you.
 
 ```sh
 # Test all the example code in Serde documentation
-cargo test
-```
-
-##### In the [`test_suite/deps`] directory
-
-```sh
-# This is a prerequisite for running the full test suite
-cargo clean && cargo update && cargo build
+cargo test --features derive
 ```
 
 ##### In the [`test_suite`] directory
 
 ```sh
 # Run the full test suite, including tests of unstable functionality
-cargo test --features unstable
+cargo +nightly test --features unstable
 ```
 
+Note that this test suite currently only supports running on a nightly compiler.
+
 [`serde`]: https://github.com/serde-rs/serde/tree/master/serde
-[`test_suite/deps`]: https://github.com/serde-rs/serde/tree/master/test_suite/deps
 [`test_suite`]: https://github.com/serde-rs/serde/tree/master/test_suite
 
 ## Conduct

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.121" # remember to update html_root_url and serde_derive dependency
+version = "1.0.128" # remember to update html_root_url and serde_derive dependency
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "A generic serialization/deserialization framework"
@@ -14,7 +14,7 @@ include = ["build.rs", "src/**/*.rs", "crates-io.md", "README.md", "LICENSE-APAC
 build = "build.rs"
 
 [dependencies]
-serde_derive = { version = "=1.0.121", optional = true, path = "../serde_derive" }
+serde_derive = { version = "=1.0.128", optional = true, path = "../serde_derive" }
 
 [dev-dependencies]
 serde_derive = { version = "1.0", path = "../serde_derive" }

serde/build.rs

@@ -53,9 +53,10 @@ fn main() {
     // 128-bit integers stabilized in Rust 1.26:
     // https://blog.rust-lang.org/2018/05/10/Rust-1.26.html
     //
-    // Disabled on Emscripten targets as Emscripten doesn't
-    // currently support integers larger than 64 bits.
-    if minor >= 26 && !emscripten {
+    // Disabled on Emscripten targets before Rust 1.40 since
+    // Emscripten did not support 128-bit integers until Rust 1.40
+    // (https://github.com/rust-lang/rust/pull/65251)
+    if minor >= 26 && (!emscripten || minor >= 40) {
         println!("cargo:rustc-cfg=integer128");
     }
 
@@ -71,12 +72,19 @@ fn main() {
         println!("cargo:rustc-cfg=num_nonzero");
     }
 
-    // TryFrom, Atomic types, and non-zero signed integers stabilized in Rust 1.34:
+    // Current minimum supported version of serde_derive crate is Rust 1.31.
+    if minor >= 31 {
+        println!("cargo:rustc-cfg=serde_derive");
+    }
+
+    // TryFrom, Atomic types, non-zero signed integers, and SystemTime::checked_add
+    // stabilized in Rust 1.34:
     // https://blog.rust-lang.org/2019/04/11/Rust-1.34.0.html#tryfrom-and-tryinto
     // https://blog.rust-lang.org/2019/04/11/Rust-1.34.0.html#library-stabilizations
     if minor >= 34 {
         println!("cargo:rustc-cfg=core_try_from");
         println!("cargo:rustc-cfg=num_nonzero_signed");
+        println!("cargo:rustc-cfg=systemtime_checked_add");
 
         // Whitelist of archs that support std::sync::atomic module. Ideally we
         // would use #[cfg(target_has_atomic = "...")] but it is not stable yet.

serde/src/de/from_primitive.rs

@@ -1,260 +0,0 @@
-use lib::*;
-
-macro_rules! int_to_int {
-    ($dst:ident, $n:ident) => {
-        if $dst::min_value() as i64 <= $n as i64 && $n as i64 <= $dst::max_value() as i64 {
-            Some($n as $dst)
-        } else {
-            None
-        }
-    };
-}
-
-macro_rules! int_to_uint {
-    ($dst:ident, $n:ident) => {
-        if 0 <= $n && $n as u64 <= $dst::max_value() as u64 {
-            Some($n as $dst)
-        } else {
-            None
-        }
-    };
-}
-
-macro_rules! uint_to {
-    ($dst:ident, $n:ident) => {
-        if $n as u64 <= $dst::max_value() as u64 {
-            Some($n as $dst)
-        } else {
-            None
-        }
-    };
-}
-
-pub trait FromPrimitive: Sized {
-    fn from_i8(n: i8) -> Option<Self>;
-    fn from_i16(n: i16) -> Option<Self>;
-    fn from_i32(n: i32) -> Option<Self>;
-    fn from_i64(n: i64) -> Option<Self>;
-    fn from_u8(n: u8) -> Option<Self>;
-    fn from_u16(n: u16) -> Option<Self>;
-    fn from_u32(n: u32) -> Option<Self>;
-    fn from_u64(n: u64) -> Option<Self>;
-}
-
-macro_rules! impl_from_primitive_for_int {
-    ($t:ident) => {
-        impl FromPrimitive for $t {
-            #[inline]
-            fn from_i8(n: i8) -> Option<Self> {
-                int_to_int!($t, n)
-            }
-            #[inline]
-            fn from_i16(n: i16) -> Option<Self> {
-                int_to_int!($t, n)
-            }
-            #[inline]
-            fn from_i32(n: i32) -> Option<Self> {
-                int_to_int!($t, n)
-            }
-            #[inline]
-            fn from_i64(n: i64) -> Option<Self> {
-                int_to_int!($t, n)
-            }
-            #[inline]
-            fn from_u8(n: u8) -> Option<Self> {
-                uint_to!($t, n)
-            }
-            #[inline]
-            fn from_u16(n: u16) -> Option<Self> {
-                uint_to!($t, n)
-            }
-            #[inline]
-            fn from_u32(n: u32) -> Option<Self> {
-                uint_to!($t, n)
-            }
-            #[inline]
-            fn from_u64(n: u64) -> Option<Self> {
-                uint_to!($t, n)
-            }
-        }
-    };
-}
-
-macro_rules! impl_from_primitive_for_uint {
-    ($t:ident) => {
-        impl FromPrimitive for $t {
-            #[inline]
-            fn from_i8(n: i8) -> Option<Self> {
-                int_to_uint!($t, n)
-            }
-            #[inline]
-            fn from_i16(n: i16) -> Option<Self> {
-                int_to_uint!($t, n)
-            }
-            #[inline]
-            fn from_i32(n: i32) -> Option<Self> {
-                int_to_uint!($t, n)
-            }
-            #[inline]
-            fn from_i64(n: i64) -> Option<Self> {
-                int_to_uint!($t, n)
-            }
-            #[inline]
-            fn from_u8(n: u8) -> Option<Self> {
-                uint_to!($t, n)
-            }
-            #[inline]
-            fn from_u16(n: u16) -> Option<Self> {
-                uint_to!($t, n)
-            }
-            #[inline]
-            fn from_u32(n: u32) -> Option<Self> {
-                uint_to!($t, n)
-            }
-            #[inline]
-            fn from_u64(n: u64) -> Option<Self> {
-                uint_to!($t, n)
-            }
-        }
-    };
-}
-
-macro_rules! impl_from_primitive_for_float {
-    ($t:ident) => {
-        impl FromPrimitive for $t {
-            #[inline]
-            fn from_i8(n: i8) -> Option<Self> {
-                Some(n as Self)
-            }
-            #[inline]
-            fn from_i16(n: i16) -> Option<Self> {
-                Some(n as Self)
-            }
-            #[inline]
-            fn from_i32(n: i32) -> Option<Self> {
-                Some(n as Self)
-            }
-            #[inline]
-            fn from_i64(n: i64) -> Option<Self> {
-                Some(n as Self)
-            }
-            #[inline]
-            fn from_u8(n: u8) -> Option<Self> {
-                Some(n as Self)
-            }
-            #[inline]
-            fn from_u16(n: u16) -> Option<Self> {
-                Some(n as Self)
-            }
-            #[inline]
-            fn from_u32(n: u32) -> Option<Self> {
-                Some(n as Self)
-            }
-            #[inline]
-            fn from_u64(n: u64) -> Option<Self> {
-                Some(n as Self)
-            }
-        }
-    };
-}
-
-impl_from_primitive_for_int!(isize);
-impl_from_primitive_for_int!(i8);
-impl_from_primitive_for_int!(i16);
-impl_from_primitive_for_int!(i32);
-impl_from_primitive_for_int!(i64);
-impl_from_primitive_for_uint!(usize);
-impl_from_primitive_for_uint!(u8);
-impl_from_primitive_for_uint!(u16);
-impl_from_primitive_for_uint!(u32);
-impl_from_primitive_for_uint!(u64);
-impl_from_primitive_for_float!(f32);
-impl_from_primitive_for_float!(f64);
-
-serde_if_integer128! {
-    impl FromPrimitive for i128 {
-        #[inline]
-        fn from_i8(n: i8) -> Option<Self> {
-            Some(n as i128)
-        }
-        #[inline]
-        fn from_i16(n: i16) -> Option<Self> {
-            Some(n as i128)
-        }
-        #[inline]
-        fn from_i32(n: i32) -> Option<Self> {
-            Some(n as i128)
-        }
-        #[inline]
-        fn from_i64(n: i64) -> Option<Self> {
-            Some(n as i128)
-        }
-        #[inline]
-        fn from_u8(n: u8) -> Option<Self> {
-            Some(n as i128)
-        }
-        #[inline]
-        fn from_u16(n: u16) -> Option<Self> {
-            Some(n as i128)
-        }
-        #[inline]
-        fn from_u32(n: u32) -> Option<Self> {
-            Some(n as i128)
-        }
-        #[inline]
-        fn from_u64(n: u64) -> Option<Self> {
-            Some(n as i128)
-        }
-    }
-
-    impl FromPrimitive for u128 {
-        #[inline]
-        fn from_i8(n: i8) -> Option<Self> {
-            if n >= 0 {
-                Some(n as u128)
-            } else {
-                None
-            }
-        }
-        #[inline]
-        fn from_i16(n: i16) -> Option<Self> {
-            if n >= 0 {
-                Some(n as u128)
-            } else {
-                None
-            }
-        }
-        #[inline]
-        fn from_i32(n: i32) -> Option<Self> {
-            if n >= 0 {
-                Some(n as u128)
-            } else {
-                None
-            }
-        }
-        #[inline]
-        fn from_i64(n: i64) -> Option<Self> {
-            if n >= 0 {
-                Some(n as u128)
-            } else {
-                None
-            }
-        }
-        #[inline]
-        fn from_u8(n: u8) -> Option<Self> {
-            Some(n as u128)
-        }
-        #[inline]
-        fn from_u16(n: u16) -> Option<Self> {
-            Some(n as u128)
-        }
-        #[inline]
-        fn from_u32(n: u32) -> Option<Self> {
-            Some(n as u128)
-        }
-        #[inline]
-        fn from_u64(n: u64) -> Option<Self> {
-            Some(n as u128)
-        }
-    }
-}

serde/src/de/impls.rs

@@ -7,11 +7,10 @@ use de::{
 #[cfg(any(core_duration, feature = "std", feature = "alloc"))]
 use de::MapAccess;
 
-use __private::de::InPlaceSeed;
-use de::from_primitive::FromPrimitive;
+use seed::InPlaceSeed;
 
 #[cfg(any(feature = "std", feature = "alloc"))]
-use __private::de::size_hint;
+use __private::size_hint;
 
 ////////////////////////////////////////////////////////////////////////////////
 
@@ -81,38 +80,8 @@ impl<'de> Deserialize<'de> for bool {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-macro_rules! visit_integer_method {
-    ($src_ty:ident, $method:ident, $from_method:ident, $group:ident, $group_ty:ident) => {
-        #[inline]
-        fn $method<E>(self, v: $src_ty) -> Result<Self::Value, E>
-        where
-            E: Error,
-        {
-            match FromPrimitive::$from_method(v) {
-                Some(v) => Ok(v),
-                None => Err(Error::invalid_value(
-                    Unexpected::$group(v as $group_ty),
-                    &self,
-                )),
-            }
-        }
-    };
-}
-
-macro_rules! visit_float_method {
-    ($src_ty:ident, $method:ident) => {
-        #[inline]
-        fn $method<E>(self, v: $src_ty) -> Result<Self::Value, E>
-        where
-            E: Error,
-        {
-            Ok(v as Self::Value)
-        }
-    };
-}
-
 macro_rules! impl_deserialize_num {
-    ($ty:ident, $method:ident, $($visit:ident),*) => {
+    ($ty:ident, $deserialize:ident $($methods:tt)*) => {
         impl<'de> Deserialize<'de> for $ty {
             #[inline]
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
@@ -128,131 +97,221 @@ macro_rules! impl_deserialize_num {
                         formatter.write_str(stringify!($ty))
                     }
 
-                    $(
-                        impl_deserialize_num!($visit $ty);
-                    )*
+                    $($methods)*
                 }
 
-                deserializer.$method(PrimitiveVisitor)
+                deserializer.$deserialize(PrimitiveVisitor)
             }
         }
     };
-
-    (integer $ty:ident) => {
-        visit_integer_method!(i8, visit_i8, from_i8, Signed, i64);
-        visit_integer_method!(i16, visit_i16, from_i16, Signed, i64);
-        visit_integer_method!(i32, visit_i32, from_i32, Signed, i64);
-        visit_integer_method!(i64, visit_i64, from_i64, Signed, i64);
-
-        visit_integer_method!(u8, visit_u8, from_u8, Unsigned, u64);
-        visit_integer_method!(u16, visit_u16, from_u16, Unsigned, u64);
-        visit_integer_method!(u32, visit_u32, from_u32, Unsigned, u64);
-        visit_integer_method!(u64, visit_u64, from_u64, Unsigned, u64);
-    };
-
-    (float $ty:ident) => {
-        visit_float_method!(f32, visit_f32);
-        visit_float_method!(f64, visit_f64);
-    };
 }
 
-impl_deserialize_num!(i8, deserialize_i8, integer);
-impl_deserialize_num!(i16, deserialize_i16, integer);
-impl_deserialize_num!(i32, deserialize_i32, integer);
-impl_deserialize_num!(i64, deserialize_i64, integer);
-impl_deserialize_num!(isize, deserialize_i64, integer);
-
-impl_deserialize_num!(u8, deserialize_u8, integer);
-impl_deserialize_num!(u16, deserialize_u16, integer);
-impl_deserialize_num!(u32, deserialize_u32, integer);
-impl_deserialize_num!(u64, deserialize_u64, integer);
-impl_deserialize_num!(usize, deserialize_u64, integer);
-
-impl_deserialize_num!(f32, deserialize_f32, integer, float);
-impl_deserialize_num!(f64, deserialize_f64, integer, float);
-
-serde_if_integer128! {
-    impl<'de> Deserialize<'de> for i128 {
+macro_rules! num_self {
+    ($ty:ident : $visit:ident) => {
         #[inline]
-        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        fn $visit<E>(self, v: $ty) -> Result<Self::Value, E>
         where
-            D: Deserializer<'de>,
+            E: Error,
         {
-            struct PrimitiveVisitor;
+            Ok(v)
+        }
+    };
+}
 
-            impl<'de> Visitor<'de> for PrimitiveVisitor {
-                type Value = i128;
+macro_rules! num_as_self {
+    ($($ty:ident : $visit:ident)*) => {
+        $(
+            #[inline]
+            fn $visit<E>(self, v: $ty) -> Result<Self::Value, E>
+            where
+                E: Error,
+            {
+                Ok(v as Self::Value)
+            }
+        )*
+    };
+}
 
-                fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                    formatter.write_str("i128")
-                }
-
-                impl_deserialize_num!(integer i128);
-
-                #[inline]
-                fn visit_i128<E>(self, v: i128) -> Result<Self::Value, E>
-                where
-                    E: Error,
-                {
-                    Ok(v)
-                }
-
-                #[inline]
-                fn visit_u128<E>(self, v: u128) -> Result<Self::Value, E>
-                where
-                    E: Error,
-                {
-                    if v <= i128::max_value() as u128 {
-                        Ok(v as i128)
-                    } else {
-                        Err(Error::invalid_value(Unexpected::Other("u128"), &self))
-                    }
+macro_rules! int_to_int {
+    ($($ty:ident : $visit:ident)*) => {
+        $(
+            #[inline]
+            fn $visit<E>(self, v: $ty) -> Result<Self::Value, E>
+            where
+                E: Error,
+            {
+                if Self::Value::min_value() as i64 <= v as i64 && v as i64 <= Self::Value::max_value() as i64 {
+                    Ok(v as Self::Value)
+                } else {
+                    Err(Error::invalid_value(Unexpected::Signed(v as i64), &self))
                 }
             }
+        )*
+    };
+}
 
-            deserializer.deserialize_i128(PrimitiveVisitor)
+macro_rules! int_to_uint {
+    ($($ty:ident : $visit:ident)*) => {
+        $(
+            #[inline]
+            fn $visit<E>(self, v: $ty) -> Result<Self::Value, E>
+            where
+                E: Error,
+            {
+                if 0 <= v && v as u64 <= Self::Value::max_value() as u64 {
+                    Ok(v as Self::Value)
+                } else {
+                    Err(Error::invalid_value(Unexpected::Signed(v as i64), &self))
+                }
+            }
+        )*
+    };
+}
+
+macro_rules! uint_to_self {
+    ($($ty:ident : $visit:ident)*) => {
+        $(
+            #[inline]
+            fn $visit<E>(self, v: $ty) -> Result<Self::Value, E>
+            where
+                E: Error,
+            {
+                if v as u64 <= Self::Value::max_value() as u64 {
+                    Ok(v as Self::Value)
+                } else {
+                    Err(Error::invalid_value(Unexpected::Unsigned(v as u64), &self))
+                }
+            }
+        )*
+    };
+}
+
+impl_deserialize_num! {
+    i8, deserialize_i8
+    num_self!(i8:visit_i8);
+    int_to_int!(i16:visit_i16 i32:visit_i32 i64:visit_i64);
+    uint_to_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+}
+
+impl_deserialize_num! {
+    i16, deserialize_i16
+    num_self!(i16:visit_i16);
+    num_as_self!(i8:visit_i8);
+    int_to_int!(i32:visit_i32 i64:visit_i64);
+    uint_to_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+}
+
+impl_deserialize_num! {
+    i32, deserialize_i32
+    num_self!(i32:visit_i32);
+    num_as_self!(i8:visit_i8 i16:visit_i16);
+    int_to_int!(i64:visit_i64);
+    uint_to_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+}
+
+impl_deserialize_num! {
+    i64, deserialize_i64
+    num_self!(i64:visit_i64);
+    num_as_self!(i8:visit_i8 i16:visit_i16 i32:visit_i32);
+    uint_to_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+}
+
+impl_deserialize_num! {
+    isize, deserialize_i64
+    num_as_self!(i8:visit_i8 i16:visit_i16);
+    int_to_int!(i32:visit_i32 i64:visit_i64);
+    uint_to_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+}
+
+impl_deserialize_num! {
+    u8, deserialize_u8
+    num_self!(u8:visit_u8);
+    int_to_uint!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+    uint_to_self!(u16:visit_u16 u32:visit_u32 u64:visit_u64);
+}
+
+impl_deserialize_num! {
+    u16, deserialize_u16
+    num_self!(u16:visit_u16);
+    num_as_self!(u8:visit_u8);
+    int_to_uint!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+    uint_to_self!(u32:visit_u32 u64:visit_u64);
+}
+
+impl_deserialize_num! {
+    u32, deserialize_u32
+    num_self!(u32:visit_u32);
+    num_as_self!(u8:visit_u8 u16:visit_u16);
+    int_to_uint!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+    uint_to_self!(u64:visit_u64);
+}
+
+impl_deserialize_num! {
+    u64, deserialize_u64
+    num_self!(u64:visit_u64);
+    num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32);
+    int_to_uint!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+}
+
+impl_deserialize_num! {
+    usize, deserialize_u64
+    num_as_self!(u8:visit_u8 u16:visit_u16);
+    int_to_uint!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+    uint_to_self!(u32:visit_u32 u64:visit_u64);
+}
+
+impl_deserialize_num! {
+    f32, deserialize_f32
+    num_self!(f32:visit_f32);
+    num_as_self!(f64:visit_f64);
+    num_as_self!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+    num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+}
+
+impl_deserialize_num! {
+    f64, deserialize_f64
+    num_self!(f64:visit_f64);
+    num_as_self!(f32:visit_f32);
+    num_as_self!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+    num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+}
+
+serde_if_integer128! {
+    impl_deserialize_num! {
+        i128, deserialize_i128
+        num_self!(i128:visit_i128);
+        num_as_self!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+        num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+
+        #[inline]
+        fn visit_u128<E>(self, v: u128) -> Result<Self::Value, E>
+        where
+            E: Error,
+        {
+            if v <= i128::max_value() as u128 {
+                Ok(v as i128)
+            } else {
+                Err(Error::invalid_value(Unexpected::Other("u128"), &self))
+            }
         }
     }
 
-    impl<'de> Deserialize<'de> for u128 {
+    impl_deserialize_num! {
+        u128, deserialize_u128
+        num_self!(u128:visit_u128);
+        num_as_self!(u8:visit_u8 u16:visit_u16 u32:visit_u32 u64:visit_u64);
+        int_to_uint!(i8:visit_i8 i16:visit_i16 i32:visit_i32 i64:visit_i64);
+
         #[inline]
-        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        fn visit_i128<E>(self, v: i128) -> Result<Self::Value, E>
         where
-            D: Deserializer<'de>,
+            E: Error,
         {
-            struct PrimitiveVisitor;
-
-            impl<'de> Visitor<'de> for PrimitiveVisitor {
-                type Value = u128;
-
-                fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                    formatter.write_str("u128")
-                }
-
-                impl_deserialize_num!(integer u128);
-
-                #[inline]
-                fn visit_i128<E>(self, v: i128) -> Result<Self::Value, E>
-                where
-                    E: Error,
-                {
-                    if v >= 0 {
-                        Ok(v as u128)
-                    } else {
-                        Err(Error::invalid_value(Unexpected::Other("i128"), &self))
-                    }
-                }
-
-                #[inline]
-                fn visit_u128<E>(self, v: u128) -> Result<Self::Value, E>
-                where
-                    E: Error,
-                {
-                    Ok(v)
-                }
+            if 0 <= v {
+                Ok(v as u128)
+            } else {
+                Err(Error::invalid_value(Unexpected::Other("i128"), &self))
             }
-
-            deserializer.deserialize_u128(PrimitiveVisitor)
         }
     }
 }
@@ -1987,6 +2046,17 @@ impl<'de> Deserialize<'de> for SystemTime {
             }
         }
 
+        fn check_overflow<E>(secs: u64, nanos: u32) -> Result<(), E>
+        where
+            E: Error,
+        {
+            static NANOS_PER_SEC: u32 = 1_000_000_000;
+            match secs.checked_add((nanos / NANOS_PER_SEC) as u64) {
+                Some(_) => Ok(()),
+                None => Err(E::custom("overflow deserializing SystemTime epoch offset")),
+            }
+        }
+
         struct DurationVisitor;
 
         impl<'de> Visitor<'de> for DurationVisitor {
@@ -2012,6 +2082,7 @@ impl<'de> Deserialize<'de> for SystemTime {
                         return Err(Error::invalid_length(1, &self));
                     }
                 };
+                try!(check_overflow(secs, nanos));
                 Ok(Duration::new(secs, nanos))
             }
 
@@ -2049,13 +2120,20 @@ impl<'de> Deserialize<'de> for SystemTime {
                     Some(nanos) => nanos,
                     None => return Err(<A::Error as Error>::missing_field("nanos_since_epoch")),
                 };
+                try!(check_overflow(secs, nanos));
                 Ok(Duration::new(secs, nanos))
             }
         }
 
         const FIELDS: &'static [&'static str] = &["secs_since_epoch", "nanos_since_epoch"];
         let duration = try!(deserializer.deserialize_struct("SystemTime", FIELDS, DurationVisitor));
-        Ok(UNIX_EPOCH + duration)
+        #[cfg(systemtime_checked_add)]
+        let ret = UNIX_EPOCH
+            .checked_add(duration)
+            .ok_or_else(|| D::Error::custom("overflow deserializing SystemTime"));
+        #[cfg(not(systemtime_checked_add))]
+        let ret = Ok(UNIX_EPOCH + duration);
+        ret
     }
 }
 

serde/src/de/mod.rs

@@ -118,7 +118,6 @@ use lib::*;
 
 pub mod value;
 
-mod from_primitive;
 mod ignored_any;
 mod impls;
 mod utf8;
@@ -393,7 +392,7 @@ pub enum Unexpected<'a> {
 }
 
 impl<'a> fmt::Display for Unexpected<'a> {
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         use self::Unexpected::*;
         match *self {
             Bool(b) => write!(formatter, "boolean `{}`", b),
@@ -1008,7 +1007,7 @@ pub trait Deserializer<'de>: Sized {
     /// `Deserializer`.
     ///
     /// If the `Visitor` would benefit from taking ownership of `String` data,
-    /// indiciate this to the `Deserializer` by using `deserialize_string`
+    /// indicate this to the `Deserializer` by using `deserialize_string`
     /// instead.
     fn deserialize_str<V>(self, visitor: V) -> Result<V::Value, Self::Error>
     where

serde/src/de/seed.rs

@@ -0,0 +1,19 @@
+use de::{Deserialize, DeserializeSeed, Deserializer};
+
+/// A DeserializeSeed helper for implementing deserialize_in_place Visitors.
+///
+/// Wraps a mutable reference and calls deserialize_in_place on it.
+pub struct InPlaceSeed<'a, T: 'a>(pub &'a mut T);
+
+impl<'a, 'de, T> DeserializeSeed<'de> for InPlaceSeed<'a, T>
+where
+    T: Deserialize<'de>,
+{
+    type Value = ();
+    fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        T::deserialize_in_place(deserializer, self.0)
+    }
+}

serde/src/de/value.rs

@@ -24,7 +24,7 @@
 use lib::*;
 
 use self::private::{First, Second};
-use __private::de::size_hint;
+use __private::size_hint;
 use de::{self, Deserializer, Expected, IntoDeserializer, SeqAccess, Visitor};
 use ser;
 
@@ -48,7 +48,7 @@ macro_rules! impl_copy_clone {
 
 /// A minimal representation of all possible errors that can occur using the
 /// `IntoDeserializer` trait.
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, PartialEq)]
 pub struct Error {
     err: ErrorImpl,
 }
@@ -93,16 +93,25 @@ impl ser::Error for Error {
 
 impl Display for Error {
     #[cfg(any(feature = "std", feature = "alloc"))]
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         formatter.write_str(&self.err)
     }
 
     #[cfg(not(any(feature = "std", feature = "alloc")))]
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         formatter.write_str("Serde deserialization error")
     }
 }
 
+impl Debug for Error {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = formatter.debug_tuple("Error");
+        #[cfg(any(feature = "std", feature = "alloc"))]
+        debug.field(&self.err);
+        debug.finish()
+    }
+}
+
 #[cfg(feature = "std")]
 impl error::Error for Error {
     fn description(&self) -> &str {
@@ -126,7 +135,6 @@ where
 }
 
 /// A deserializer holding a `()`.
-#[derive(Debug)]
 pub struct UnitDeserializer<E> {
     marker: PhantomData<E>,
 }
@@ -160,6 +168,12 @@ where
     }
 }
 
+impl<E> Debug for UnitDeserializer<E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.debug_struct("UnitDeserializer").finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer that cannot be instantiated.
@@ -208,7 +222,6 @@ macro_rules! primitive_deserializer {
     ($ty:ty, $doc:tt, $name:ident, $method:ident $($cast:tt)*) => {
         #[doc = "A deserializer holding"]
         #[doc = $doc]
-        #[derive(Debug)]
         pub struct $name<E> {
             value: $ty,
             marker: PhantomData<E>
@@ -249,6 +262,15 @@ macro_rules! primitive_deserializer {
                 visitor.$method(self.value $($cast)*)
             }
         }
+
+        impl<E> Debug for $name<E> {
+            fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter
+                    .debug_struct(stringify!($name))
+                    .field("value", &self.value)
+                    .finish()
+            }
+        }
     }
 }
 
@@ -272,7 +294,6 @@ serde_if_integer128! {
 }
 
 /// A deserializer holding a `u32`.
-#[derive(Debug)]
 pub struct U32Deserializer<E> {
     value: u32,
     marker: PhantomData<E>,
@@ -343,10 +364,18 @@ where
     }
 }
 
+impl<E> Debug for U32Deserializer<E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("U32Deserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer holding a `&str`.
-#[derive(Debug)]
 pub struct StrDeserializer<'a, E> {
     value: &'a str,
     marker: PhantomData<E>,
@@ -417,11 +446,19 @@ where
     }
 }
 
+impl<'a, E> Debug for StrDeserializer<'a, E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("StrDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer holding a `&str` with a lifetime tied to another
 /// deserializer.
-#[derive(Debug)]
 pub struct BorrowedStrDeserializer<'de, E> {
     value: &'de str,
     marker: PhantomData<E>,
@@ -488,11 +525,19 @@ where
     }
 }
 
+impl<'de, E> Debug for BorrowedStrDeserializer<'de, E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("BorrowedStrDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer holding a `String`.
 #[cfg(any(feature = "std", feature = "alloc"))]
-#[derive(Debug)]
 pub struct StringDeserializer<E> {
     value: String,
     marker: PhantomData<E>,
@@ -574,11 +619,20 @@ where
     }
 }
 
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<E> Debug for StringDeserializer<E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("StringDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer holding a `Cow<str>`.
 #[cfg(any(feature = "std", feature = "alloc"))]
-#[derive(Debug)]
 pub struct CowStrDeserializer<'a, E> {
     value: Cow<'a, str>,
     marker: PhantomData<E>,
@@ -663,10 +717,19 @@ where
     }
 }
 
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'a, E> Debug for CowStrDeserializer<'a, E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("CowStrDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer holding a `&[u8]`. Always calls [`Visitor::visit_bytes`].
-#[derive(Debug)]
 pub struct BytesDeserializer<'a, E> {
     value: &'a [u8],
     marker: PhantomData<E>,
@@ -684,6 +747,17 @@ impl<'a, E> BytesDeserializer<'a, E> {
 
 impl_copy_clone!(BytesDeserializer<'a>);
 
+impl<'de, 'a, E> IntoDeserializer<'de, E> for &'a [u8]
+where
+    E: de::Error,
+{
+    type Deserializer = BytesDeserializer<'a, E>;
+
+    fn into_deserializer(self) -> BytesDeserializer<'a, E> {
+        BytesDeserializer::new(self)
+    }
+}
+
 impl<'de, 'a, E> Deserializer<'de> for BytesDeserializer<'a, E>
 where
     E: de::Error,
@@ -704,9 +778,17 @@ where
     }
 }
 
+impl<'a, E> Debug for BytesDeserializer<'a, E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("BytesDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 /// A deserializer holding a `&[u8]` with a lifetime tied to another
 /// deserializer. Always calls [`Visitor::visit_borrowed_bytes`].
-#[derive(Debug)]
 pub struct BorrowedBytesDeserializer<'de, E> {
     value: &'de [u8],
     marker: PhantomData<E>,
@@ -744,10 +826,19 @@ where
     }
 }
 
+impl<'de, E> Debug for BorrowedBytesDeserializer<'de, E> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("BorrowedBytesDeserializer")
+            .field("value", &self.value)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 /// A deserializer that iterates over a sequence.
-#[derive(Clone, Debug)]
+#[derive(Clone)]
 pub struct SeqDeserializer<I, E> {
     iter: iter::Fuse<I>,
     count: usize,
@@ -852,6 +943,19 @@ impl Expected for ExpectedInSeq {
     }
 }
 
+impl<I, E> Debug for SeqDeserializer<I, E>
+where
+    I: Debug,
+{
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter
+            .debug_struct("SeqDeserializer")
+            .field("iter", &self.iter)
+            .field("count", &self.count)
+            .finish()
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 #[cfg(any(feature = "std", feature = "alloc"))]
@@ -1147,7 +1251,6 @@ where
     }
 }
 
-// Cannot #[derive(Debug)] because of the bound `Second<I::Item>: Debug`.
 impl<'de, I, E> Debug for MapDeserializer<'de, I, E>
 where
     I: Iterator + Debug,
@@ -1160,8 +1263,6 @@ where
             .field("iter", &self.iter)
             .field("value", &self.value)
             .field("count", &self.count)
-            .field("lifetime", &self.lifetime)
-            .field("error", &self.error)
             .finish()
     }
 }
@@ -1370,7 +1471,6 @@ mod private {
 
     use de::{self, DeserializeSeed, Deserializer, MapAccess, Unexpected, VariantAccess, Visitor};
 
-    #[derive(Clone, Debug)]
     pub struct UnitOnly<E> {
         marker: PhantomData<E>,
     }
@@ -1429,7 +1529,6 @@ mod private {
         }
     }
 
-    #[derive(Clone, Debug)]
     pub struct MapAsEnum<A> {
         map: A,
     }

serde/src/integer128.rs

@@ -10,7 +10,7 @@
 /// bother with this macro and may assume support for 128-bit integers.
 ///
 /// ```edition2018
-/// # use serde::__private::ser::Error;
+/// # use serde::__private::doc::Error;
 /// #
 /// # struct MySerializer;
 /// #

serde/src/lib.rs

@@ -44,7 +44,7 @@
 //! - [BSON], the data storage and network transfer format used by MongoDB.
 //! - [Avro], a binary format used within Apache Hadoop, with support for schema
 //!   definition.
-//! - [JSON5], A superset of JSON including some productions from ES5.
+//! - [JSON5], a superset of JSON including some productions from ES5.
 //! - [Postcard], a no\_std and embedded-systems friendly compact binary format.
 //! - [URL] query strings, in the x-www-form-urlencoded format.
 //! - [Envy], a way to deserialize environment variables into Rust structs.
@@ -84,7 +84,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.121")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.128")]
 // Support using Serde without the standard library!
 #![cfg_attr(not(feature = "std"), no_std)]
 // Unstable functionality only if the user asks for it. For tracking and
@@ -120,6 +120,7 @@
         zero_prefixed_literal,
         // correctly used
         enum_glob_use,
+        let_underscore_drop,
         map_err_ignore,
         result_unit_err,
         wildcard_imports,
@@ -138,7 +139,6 @@
     )
 )]
 // Rustc lints.
-#![forbid(unsafe_code)]
 #![deny(missing_docs, unused_imports)]
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -276,6 +276,9 @@ use self::__private as export;
 #[allow(unused_imports)]
 use self::__private as private;
 
+#[path = "de/seed.rs"]
+mod seed;
+
 #[cfg(not(feature = "std"))]
 mod std_error;
 

serde/src/private/de.rs

@@ -1,10 +1,10 @@
 use lib::*;
 
 use de::value::{BorrowedBytesDeserializer, BytesDeserializer};
-use de::{Deserialize, DeserializeSeed, Deserializer, Error, IntoDeserializer, Visitor};
+use de::{Deserialize, Deserializer, Error, IntoDeserializer, Visitor};
 
 #[cfg(any(feature = "std", feature = "alloc"))]
-use de::{MapAccess, Unexpected};
+use de::{DeserializeSeed, MapAccess, Unexpected};
 
 #[cfg(any(feature = "std", feature = "alloc"))]
 pub use self::content::{
@@ -13,6 +13,8 @@ pub use self::content::{
     TagOrContentField, TagOrContentFieldVisitor, TaggedContentVisitor, UntaggedUnitVisitor,
 };
 
+pub use seed::InPlaceSeed;
+
 /// If the missing field is of type `Option<T>` then treat is as `None`,
 /// otherwise it is an error.
 pub fn missing_field<'de, V, E>(field: &'static str) -> Result<V, E>
@@ -189,29 +191,6 @@ where
         .map(From::from)
 }
 
-pub mod size_hint {
-    use lib::*;
-
-    pub fn from_bounds<I>(iter: &I) -> Option<usize>
-    where
-        I: Iterator,
-    {
-        helper(iter.size_hint())
-    }
-
-    #[inline]
-    pub fn cautious(hint: Option<usize>) -> usize {
-        cmp::min(hint.unwrap_or(0), 4096)
-    }
-
-    fn helper(bounds: (usize, Option<usize>)) -> Option<usize> {
-        match bounds {
-            (lower, Some(upper)) if lower == upper => Some(upper),
-            _ => None,
-        }
-    }
-}
-
 #[cfg(any(feature = "std", feature = "alloc"))]
 mod content {
     // This module is private and nothing here should be used outside of
@@ -226,7 +205,7 @@ mod content {
 
     use lib::*;
 
-    use super::size_hint;
+    use __private::size_hint;
     use de::{
         self, Deserialize, DeserializeSeed, Deserializer, EnumAccess, Expected, IgnoredAny,
         MapAccess, SeqAccess, Unexpected, Visitor,
@@ -825,15 +804,17 @@ mod content {
     /// Not public API.
     pub struct TaggedContentVisitor<'de, T> {
         tag_name: &'static str,
+        expecting: &'static str,
         value: PhantomData<TaggedContent<'de, T>>,
     }
 
     impl<'de, T> TaggedContentVisitor<'de, T> {
         /// Visitor for the content of an internally tagged enum with the given
         /// tag name.
-        pub fn new(name: &'static str) -> Self {
+        pub fn new(name: &'static str, expecting: &'static str) -> Self {
             TaggedContentVisitor {
                 tag_name: name,
+                expecting: expecting,
                 value: PhantomData,
             }
         }
@@ -862,7 +843,7 @@ mod content {
         type Value = TaggedContent<'de, T>;
 
         fn expecting(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-            fmt.write_str("internally tagged enum")
+            fmt.write_str(self.expecting)
         }
 
         fn visit_seq<S>(self, mut seq: S) -> Result<Self::Value, S::Error>
@@ -1041,6 +1022,25 @@ mod content {
                 _ => Err(self.invalid_type(&visitor)),
             }
         }
+
+        fn deserialize_float<V>(self, visitor: V) -> Result<V::Value, E>
+        where
+            V: Visitor<'de>,
+        {
+            match self.content {
+                Content::F32(v) => visitor.visit_f32(v),
+                Content::F64(v) => visitor.visit_f64(v),
+                Content::U8(v) => visitor.visit_u8(v),
+                Content::U16(v) => visitor.visit_u16(v),
+                Content::U32(v) => visitor.visit_u32(v),
+                Content::U64(v) => visitor.visit_u64(v),
+                Content::I8(v) => visitor.visit_i8(v),
+                Content::I16(v) => visitor.visit_i16(v),
+                Content::I32(v) => visitor.visit_i32(v),
+                Content::I64(v) => visitor.visit_i64(v),
+                _ => Err(self.invalid_type(&visitor)),
+            }
+        }
     }
 
     fn visit_content_seq<'de, V, E>(content: Vec<Content<'de>>, visitor: V) -> Result<V::Value, E>
@@ -1180,25 +1180,14 @@ mod content {
         where
             V: Visitor<'de>,
         {
-            match self.content {
-                Content::F32(v) => visitor.visit_f32(v),
-                Content::F64(v) => visitor.visit_f64(v),
-                Content::U64(v) => visitor.visit_u64(v),
-                Content::I64(v) => visitor.visit_i64(v),
-                _ => Err(self.invalid_type(&visitor)),
-            }
+            self.deserialize_float(visitor)
         }
 
         fn deserialize_f64<V>(self, visitor: V) -> Result<V::Value, Self::Error>
         where
             V: Visitor<'de>,
         {
-            match self.content {
-                Content::F64(v) => visitor.visit_f64(v),
-                Content::U64(v) => visitor.visit_u64(v),
-                Content::I64(v) => visitor.visit_i64(v),
-                _ => Err(self.invalid_type(&visitor)),
-            }
+            self.deserialize_float(visitor)
         }
 
         fn deserialize_char<V>(self, visitor: V) -> Result<V::Value, Self::Error>
@@ -1298,8 +1287,9 @@ mod content {
                 //     }
                 //
                 // We want {"topic":"Info"} to deserialize even though
-                // ordinarily unit structs do not deserialize from empty map.
+                // ordinarily unit structs do not deserialize from empty map/seq.
                 Content::Map(ref v) if v.is_empty() => visitor.visit_unit(),
+                Content::Seq(ref v) if v.is_empty() => visitor.visit_unit(),
                 _ => self.deserialize_any(visitor),
             }
         }
@@ -1752,6 +1742,25 @@ mod content {
                 _ => Err(self.invalid_type(&visitor)),
             }
         }
+
+        fn deserialize_float<V>(self, visitor: V) -> Result<V::Value, E>
+        where
+            V: Visitor<'de>,
+        {
+            match *self.content {
+                Content::F32(v) => visitor.visit_f32(v),
+                Content::F64(v) => visitor.visit_f64(v),
+                Content::U8(v) => visitor.visit_u8(v),
+                Content::U16(v) => visitor.visit_u16(v),
+                Content::U32(v) => visitor.visit_u32(v),
+                Content::U64(v) => visitor.visit_u64(v),
+                Content::I8(v) => visitor.visit_i8(v),
+                Content::I16(v) => visitor.visit_i16(v),
+                Content::I32(v) => visitor.visit_i32(v),
+                Content::I64(v) => visitor.visit_i64(v),
+                _ => Err(self.invalid_type(&visitor)),
+            }
+        }
     }
 
     fn visit_content_seq_ref<'a, 'de, V, E>(
@@ -1899,25 +1908,14 @@ mod content {
         where
             V: Visitor<'de>,
         {
-            match *self.content {
-                Content::F32(v) => visitor.visit_f32(v),
-                Content::F64(v) => visitor.visit_f64(v),
-                Content::U64(v) => visitor.visit_u64(v),
-                Content::I64(v) => visitor.visit_i64(v),
-                _ => Err(self.invalid_type(&visitor)),
-            }
+            self.deserialize_float(visitor)
         }
 
         fn deserialize_f64<V>(self, visitor: V) -> Result<V::Value, Self::Error>
         where
             V: Visitor<'de>,
         {
-            match *self.content {
-                Content::F64(v) => visitor.visit_f64(v),
-                Content::U64(v) => visitor.visit_u64(v),
-                Content::I64(v) => visitor.visit_i64(v),
-                _ => Err(self.invalid_type(&visitor)),
-            }
+            self.deserialize_float(visitor)
         }
 
         fn deserialize_char<V>(self, visitor: V) -> Result<V::Value, Self::Error>
@@ -2539,26 +2537,21 @@ mod content {
 //    }
 pub trait IdentifierDeserializer<'de, E: Error> {
     type Deserializer: Deserializer<'de, Error = E>;
-    type BorrowedDeserializer: Deserializer<'de, Error = E>;
 
     fn from(self) -> Self::Deserializer;
-    fn borrowed(self) -> Self::BorrowedDeserializer;
 }
 
-impl<'de, E> IdentifierDeserializer<'de, E> for u32
+pub struct Borrowed<'de, T: 'de + ?Sized>(pub &'de T);
+
+impl<'de, E> IdentifierDeserializer<'de, E> for u64
 where
     E: Error,
 {
-    type Deserializer = <u32 as IntoDeserializer<'de, E>>::Deserializer;
-    type BorrowedDeserializer = <u32 as IntoDeserializer<'de, E>>::Deserializer;
+    type Deserializer = <u64 as IntoDeserializer<'de, E>>::Deserializer;
 
     fn from(self) -> Self::Deserializer {
         self.into_deserializer()
     }
-
-    fn borrowed(self) -> Self::BorrowedDeserializer {
-        self.into_deserializer()
-    }
 }
 
 pub struct StrDeserializer<'a, E> {
@@ -2616,7 +2609,6 @@ where
     E: Error,
 {
     type Deserializer = StrDeserializer<'a, E>;
-    type BorrowedDeserializer = BorrowedStrDeserializer<'a, E>;
 
     fn from(self) -> Self::Deserializer {
         StrDeserializer {
@@ -2624,10 +2616,17 @@ where
             marker: PhantomData,
         }
     }
+}
 
-    fn borrowed(self) -> Self::BorrowedDeserializer {
+impl<'de, E> IdentifierDeserializer<'de, E> for Borrowed<'de, str>
+where
+    E: Error,
+{
+    type Deserializer = BorrowedStrDeserializer<'de, E>;
+
+    fn from(self) -> Self::Deserializer {
         BorrowedStrDeserializer {
-            value: self,
+            value: self.0,
             marker: PhantomData,
         }
     }
@@ -2638,32 +2637,20 @@ where
     E: Error,
 {
     type Deserializer = BytesDeserializer<'a, E>;
-    type BorrowedDeserializer = BorrowedBytesDeserializer<'a, E>;
 
     fn from(self) -> Self::Deserializer {
         BytesDeserializer::new(self)
     }
-
-    fn borrowed(self) -> Self::BorrowedDeserializer {
-        BorrowedBytesDeserializer::new(self)
-    }
 }
 
-/// A DeserializeSeed helper for implementing deserialize_in_place Visitors.
-///
-/// Wraps a mutable reference and calls deserialize_in_place on it.
-pub struct InPlaceSeed<'a, T: 'a>(pub &'a mut T);
-
-impl<'a, 'de, T> DeserializeSeed<'de> for InPlaceSeed<'a, T>
+impl<'de, E> IdentifierDeserializer<'de, E> for Borrowed<'de, [u8]>
 where
-    T: Deserialize<'de>,
+    E: Error,
 {
-    type Value = ();
-    fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
-    where
-        D: Deserializer<'de>,
-    {
-        T::deserialize_in_place(deserializer, self.0)
+    type Deserializer = BorrowedBytesDeserializer<'de, E>;
+
+    fn from(self) -> Self::Deserializer {
+        BorrowedBytesDeserializer::new(self.0)
     }
 }
 
@@ -2845,7 +2832,7 @@ where
     where
         T: DeserializeSeed<'de>,
     {
-        while let Some(item) = self.iter.next() {
+        for item in &mut self.iter {
             // Items in the vector are nulled out when used by a struct.
             if let Some((ref key, ref content)) = *item {
                 self.pending_content = Some(content);
@@ -2947,7 +2934,7 @@ where
     where
         T: DeserializeSeed<'de>,
     {
-        while let Some(item) = self.iter.next() {
+        for item in &mut self.iter {
             if let Some((ref key, ref content)) = *item {
                 // Do not take(), instead borrow this entry. The internally tagged
                 // enum does its own buffering so we can't tell whether this entry

serde/src/private/doc.rs

@@ -1,3 +1,35 @@
+// Used only by Serde doc tests. Not public API.
+
+use lib::*;
+
+use ser;
+
+#[doc(hidden)]
+#[derive(Debug)]
+pub struct Error;
+
+impl ser::Error for Error {
+    fn custom<T>(_: T) -> Self
+    where
+        T: Display,
+    {
+        unimplemented!()
+    }
+}
+
+#[cfg(feature = "std")]
+impl error::Error for Error {
+    fn description(&self) -> &str {
+        unimplemented!()
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
+        unimplemented!()
+    }
+}
+
 #[doc(hidden)]
 #[macro_export]
 macro_rules! __private_serialize {
@@ -10,19 +42,6 @@ macro_rules! __private_serialize {
     };
 }
 
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __private_deserialize {
-    () => {
-        trait Deserialize<'de>: Sized {
-            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-            where
-                D: $crate::Deserializer<'de>;
-        }
-    };
-}
-
-/// Used only by Serde doc tests. Not public API.
 #[doc(hidden)]
 #[macro_export(local_inner_macros)]
 macro_rules! __serialize_unimplemented {

serde/src/private/mod.rs

@@ -1,8 +1,13 @@
-mod macros;
-
+#[cfg(serde_derive)]
 pub mod de;
+#[cfg(serde_derive)]
 pub mod ser;
 
+pub mod size_hint;
+
+// FIXME: #[cfg(doctest)] once https://github.com/rust-lang/rust/issues/67295 is fixed.
+pub mod doc;
+
 pub use lib::clone::Clone;
 pub use lib::convert::{From, Into};
 pub use lib::default::Default;

serde/src/private/ser.rs

@@ -335,33 +335,6 @@ where
     }
 }
 
-/// Used only by Serde doc tests. Not public API.
-#[doc(hidden)]
-#[derive(Debug)]
-pub struct Error;
-
-impl ser::Error for Error {
-    fn custom<T>(_: T) -> Self
-    where
-        T: Display,
-    {
-        unimplemented!()
-    }
-}
-
-#[cfg(feature = "std")]
-impl error::Error for Error {
-    fn description(&self) -> &str {
-        unimplemented!()
-    }
-}
-
-impl Display for Error {
-    fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result {
-        unimplemented!()
-    }
-}
-
 #[cfg(any(feature = "std", feature = "alloc"))]
 mod content {
     use lib::*;
@@ -452,7 +425,6 @@ mod content {
         }
     }
 
-    #[derive(Debug)]
     pub enum Content {
         Bool(bool),
 

serde/src/private/size_hint.rs

@@ -0,0 +1,21 @@
+use lib::*;
+
+pub fn from_bounds<I>(iter: &I) -> Option<usize>
+where
+    I: Iterator,
+{
+    helper(iter.size_hint())
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+#[inline]
+pub fn cautious(hint: Option<usize>) -> usize {
+    cmp::min(hint.unwrap_or(0), 4096)
+}
+
+fn helper(bounds: (usize, Option<usize>)) -> Option<usize> {
+    match bounds {
+        (lower, Some(upper)) if lower == upper => Some(upper),
+        _ => None,
+    }
+}

serde/src/ser/impls.rs

@@ -674,6 +674,52 @@ impl Serialize for net::IpAddr {
     }
 }
 
+#[cfg(feature = "std")]
+const DEC_DIGITS_LUT: &'static [u8] = b"\
+      0001020304050607080910111213141516171819\
+      2021222324252627282930313233343536373839\
+      4041424344454647484950515253545556575859\
+      6061626364656667686970717273747576777879\
+      8081828384858687888990919293949596979899";
+
+#[cfg(feature = "std")]
+#[inline]
+fn format_u8(mut n: u8, out: &mut [u8]) -> usize {
+    if n >= 100 {
+        let d1 = ((n % 100) << 1) as usize;
+        n /= 100;
+        out[0] = b'0' + n;
+        out[1] = DEC_DIGITS_LUT[d1];
+        out[2] = DEC_DIGITS_LUT[d1 + 1];
+        3
+    } else if n >= 10 {
+        let d1 = (n << 1) as usize;
+        out[0] = DEC_DIGITS_LUT[d1];
+        out[1] = DEC_DIGITS_LUT[d1 + 1];
+        2
+    } else {
+        out[0] = b'0' + n;
+        1
+    }
+}
+
+#[cfg(feature = "std")]
+#[test]
+fn test_format_u8() {
+    let mut i = 0u8;
+
+    loop {
+        let mut buf = [0u8; 3];
+        let written = format_u8(i, &mut buf);
+        assert_eq!(i.to_string().as_bytes(), &buf[..written]);
+
+        match i.checked_add(1) {
+            Some(next) => i = next,
+            None => break,
+        }
+    }
+}
+
 #[cfg(feature = "std")]
 impl Serialize for net::Ipv4Addr {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -683,7 +729,14 @@ impl Serialize for net::Ipv4Addr {
         if serializer.is_human_readable() {
             const MAX_LEN: usize = 15;
             debug_assert_eq!(MAX_LEN, "101.102.103.104".len());
-            serialize_display_bounded_length!(self, MAX_LEN, serializer)
+            let mut buf = [b'.'; MAX_LEN];
+            let mut written = format_u8(self.octets()[0], &mut buf);
+            for oct in &self.octets()[1..] {
+                // Skip over delimiters that we initialized buf with
+                written += format_u8(*oct, &mut buf[written + 1..]) + 1;
+            }
+            // We've only written ASCII bytes to the buffer, so it is valid UTF-8
+            serializer.serialize_str(unsafe { str::from_utf8_unchecked(&buf[..written]) })
         } else {
             self.octets().serialize(serializer)
         }

serde/src/ser/impossible.rs

@@ -17,7 +17,7 @@ use ser::{
 ///
 /// ```edition2018
 /// # use serde::ser::{Serializer, Impossible};
-/// # use serde::__private::ser::Error;
+/// # use serde::__private::doc::Error;
 /// #
 /// # struct MySerializer;
 /// #

serde/src/ser/mod.rs

@@ -711,7 +711,7 @@ pub trait Serializer: Sized {
     ///
     /// ```edition2018
     /// # use serde::ser::{Serializer, SerializeSeq};
-    /// # use serde::__private::ser::Error;
+    /// # use serde::__private::doc::Error;
     /// #
     /// # struct MySerializer;
     /// #

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.121" # remember to update html_root_url
+version = "1.0.128" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
@@ -22,7 +22,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "1.0.58", features = ["visit"] }
+syn = "1.0.60"
 
 [dev-dependencies]
 serde = { version = "1.0", path = "../serde" }

serde_derive/src/bound.rs

@@ -2,7 +2,6 @@ use std::collections::HashSet;
 
 use syn;
 use syn::punctuated::{Pair, Punctuated};
-use syn::visit::{self, Visit};
 
 use internals::ast::{Container, Data};
 use internals::{attr, ungroup};
@@ -50,7 +49,7 @@ pub fn with_where_predicates_from_fields(
     let predicates = cont
         .data
         .all_fields()
-        .flat_map(|field| from_field(&field.attrs))
+        .filter_map(|field| from_field(&field.attrs))
         .flat_map(|predicates| predicates.to_vec());
 
     let mut generics = generics.clone();
@@ -72,7 +71,7 @@ pub fn with_where_predicates_from_variants(
 
     let predicates = variants
         .iter()
-        .flat_map(|variant| from_variant(&variant.attrs))
+        .filter_map(|variant| from_variant(&variant.attrs))
         .flat_map(|predicates| predicates.to_vec());
 
     let mut generics = generics.clone();
@@ -112,7 +111,8 @@ pub fn with_bound(
         // parameters.
         associated_type_usage: Vec<&'ast syn::TypePath>,
     }
-    impl<'ast> Visit<'ast> for FindTyParams<'ast> {
+
+    impl<'ast> FindTyParams<'ast> {
         fn visit_field(&mut self, field: &'ast syn::Field) {
             if let syn::Type::Path(ty) = ungroup(&field.ty) {
                 if let Some(Pair::Punctuated(t, _)) = ty.path.segments.pairs().next() {
@@ -138,7 +138,98 @@ pub fn with_bound(
                     self.relevant_type_params.insert(id.clone());
                 }
             }
-            visit::visit_path(self, path);
+            for segment in &path.segments {
+                self.visit_path_segment(segment);
+            }
+        }
+
+        // Everything below is simply traversing the syntax tree.
+
+        fn visit_type(&mut self, ty: &'ast syn::Type) {
+            match ty {
+                syn::Type::Array(ty) => self.visit_type(&ty.elem),
+                syn::Type::BareFn(ty) => {
+                    for arg in &ty.inputs {
+                        self.visit_type(&arg.ty);
+                    }
+                    self.visit_return_type(&ty.output);
+                }
+                syn::Type::Group(ty) => self.visit_type(&ty.elem),
+                syn::Type::ImplTrait(ty) => {
+                    for bound in &ty.bounds {
+                        self.visit_type_param_bound(bound);
+                    }
+                }
+                syn::Type::Macro(ty) => self.visit_macro(&ty.mac),
+                syn::Type::Paren(ty) => self.visit_type(&ty.elem),
+                syn::Type::Path(ty) => {
+                    if let Some(qself) = &ty.qself {
+                        self.visit_type(&qself.ty);
+                    }
+                    self.visit_path(&ty.path);
+                }
+                syn::Type::Ptr(ty) => self.visit_type(&ty.elem),
+                syn::Type::Reference(ty) => self.visit_type(&ty.elem),
+                syn::Type::Slice(ty) => self.visit_type(&ty.elem),
+                syn::Type::TraitObject(ty) => {
+                    for bound in &ty.bounds {
+                        self.visit_type_param_bound(bound);
+                    }
+                }
+                syn::Type::Tuple(ty) => {
+                    for elem in &ty.elems {
+                        self.visit_type(elem);
+                    }
+                }
+
+                syn::Type::Infer(_) | syn::Type::Never(_) | syn::Type::Verbatim(_) => {}
+
+                #[cfg(test)]
+                syn::Type::__TestExhaustive(_) => unimplemented!(),
+                #[cfg(not(test))]
+                _ => {}
+            }
+        }
+
+        fn visit_path_segment(&mut self, segment: &'ast syn::PathSegment) {
+            self.visit_path_arguments(&segment.arguments);
+        }
+
+        fn visit_path_arguments(&mut self, arguments: &'ast syn::PathArguments) {
+            match arguments {
+                syn::PathArguments::None => {}
+                syn::PathArguments::AngleBracketed(arguments) => {
+                    for arg in &arguments.args {
+                        match arg {
+                            syn::GenericArgument::Type(arg) => self.visit_type(arg),
+                            syn::GenericArgument::Binding(arg) => self.visit_type(&arg.ty),
+                            syn::GenericArgument::Lifetime(_)
+                            | syn::GenericArgument::Constraint(_)
+                            | syn::GenericArgument::Const(_) => {}
+                        }
+                    }
+                }
+                syn::PathArguments::Parenthesized(arguments) => {
+                    for argument in &arguments.inputs {
+                        self.visit_type(argument);
+                    }
+                    self.visit_return_type(&arguments.output);
+                }
+            }
+        }
+
+        fn visit_return_type(&mut self, return_type: &'ast syn::ReturnType) {
+            match return_type {
+                syn::ReturnType::Default => {}
+                syn::ReturnType::Type(_, output) => self.visit_type(output),
+            }
+        }
+
+        fn visit_type_param_bound(&mut self, bound: &'ast syn::TypeParamBound) {
+            match bound {
+                syn::TypeParamBound::Trait(bound) => self.visit_path(&bound.path),
+                syn::TypeParamBound::Lifetime(_) => {}
+            }
         }
 
         // Type parameter should not be considered used by a macro path.

serde_derive/src/de.rs

@@ -8,13 +8,17 @@ use bound;
 use dummy;
 use fragment::{Expr, Fragment, Match, Stmts};
 use internals::ast::{Container, Data, Field, Style, Variant};
-use internals::{attr, ungroup, Ctxt, Derive};
+use internals::{attr, replace_receiver, ungroup, Ctxt, Derive};
 use pretend;
 
 use std::collections::BTreeSet;
 use std::ptr;
 
-pub fn expand_derive_deserialize(input: &syn::DeriveInput) -> Result<TokenStream, Vec<syn::Error>> {
+pub fn expand_derive_deserialize(
+    input: &mut syn::DeriveInput,
+) -> Result<TokenStream, Vec<syn::Error>> {
+    replace_receiver(input);
+
     let ctxt = Ctxt::new();
     let cont = match Container::from_ast(&ctxt, input, Derive::Deserialize) {
         Some(cont) => cont,
@@ -402,6 +406,7 @@ fn deserialize_unit_struct(params: &Parameters, cattrs: &attr::Container) -> Fra
     let type_name = cattrs.name().deserialize_name();
 
     let expecting = format!("unit struct {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     quote_block! {
         struct __Visitor;
@@ -459,6 +464,7 @@ fn deserialize_tuple(
         Some(variant_ident) => format!("tuple variant {}::{}", params.type_name(), variant_ident),
         None => format!("tuple struct {}", params.type_name()),
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let nfields = fields.len();
 
@@ -469,7 +475,7 @@ fn deserialize_tuple(
     };
 
     let visit_seq = Stmts(deserialize_seq(
-        &type_path, params, fields, false, cattrs, &expecting,
+        &type_path, params, fields, false, cattrs, expecting,
     ));
 
     let visitor_expr = quote! {
@@ -545,6 +551,7 @@ fn deserialize_tuple_in_place(
         Some(variant_ident) => format!("tuple variant {}::{}", params.type_name(), variant_ident),
         None => format!("tuple struct {}", params.type_name()),
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let nfields = fields.len();
 
@@ -554,7 +561,7 @@ fn deserialize_tuple_in_place(
         None
     };
 
-    let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, &expecting));
+    let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, expecting));
 
     let visitor_expr = quote! {
         __Visitor {
@@ -633,6 +640,7 @@ fn deserialize_seq(
     } else {
         format!("{} with {} elements", expecting, deserialized_count)
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let mut index_in_seq = 0_usize;
     let let_values = vars.clone().zip(fields).map(|(var, field)| {
@@ -735,6 +743,7 @@ fn deserialize_seq_in_place(
     } else {
         format!("{} with {} elements", expecting, deserialized_count)
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let mut index_in_seq = 0usize;
     let write_values = fields.iter().map(|field| {
@@ -910,9 +919,10 @@ fn deserialize_struct(
         Some(variant_ident) => format!("struct variant {}::{}", params.type_name(), variant_ident),
         None => format!("struct {}", params.type_name()),
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let visit_seq = Stmts(deserialize_seq(
-        &type_path, params, fields, true, cattrs, &expecting,
+        &type_path, params, fields, true, cattrs, expecting,
     ));
 
     let (field_visitor, fields_stmt, visit_map) = if cattrs.has_flatten() {
@@ -1051,8 +1061,9 @@ fn deserialize_struct_in_place(
         Some(variant_ident) => format!("struct variant {}::{}", params.type_name(), variant_ident),
         None => format!("struct {}", params.type_name()),
     };
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
-    let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, &expecting));
+    let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, expecting));
 
     let (field_visitor, fields_stmt, visit_map) =
         deserialize_struct_as_struct_in_place_visitor(params, fields, cattrs);
@@ -1203,6 +1214,7 @@ fn deserialize_externally_tagged_enum(
 
     let type_name = cattrs.name().deserialize_name();
     let expecting = format!("enum {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
 
     let (variants_stmt, variant_visitor) = prepare_enum_variant_enum(variants, cattrs);
 
@@ -1312,6 +1324,9 @@ fn deserialize_internally_tagged_enum(
             }
         });
 
+    let expecting = format!("internally tagged enum {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
+
     quote_block! {
         #variant_visitor
 
@@ -1319,7 +1334,7 @@ fn deserialize_internally_tagged_enum(
 
         let __tagged = try!(_serde::Deserializer::deserialize_any(
             __deserializer,
-            _serde::__private::de::TaggedContentVisitor::<__Field>::new(#tag)));
+            _serde::__private::de::TaggedContentVisitor::<__Field>::new(#tag, #expecting)));
 
         match __tagged.tag {
             #(#variant_arms)*
@@ -1362,6 +1377,7 @@ fn deserialize_adjacently_tagged_enum(
         .collect();
 
     let expecting = format!("adjacently tagged enum {}", params.type_name());
+    let expecting = cattrs.expecting().unwrap_or(&expecting);
     let type_name = cattrs.name().deserialize_name();
     let deny_unknown_fields = cattrs.deny_unknown_fields();
 
@@ -1653,6 +1669,7 @@ fn deserialize_untagged_enum(
         "data did not match any variant of untagged enum {}",
         params.type_name()
     );
+    let fallthrough_msg = cattrs.expecting().unwrap_or(&fallthrough_msg);
 
     quote_block! {
         let __content = try!(<_serde::__private::de::Content as _serde::Deserialize>::deserialize(__deserializer));
@@ -1891,23 +1908,17 @@ fn deserialize_generated_identifier(
     let (ignore_variant, fallthrough) = if !is_variant && cattrs.has_flatten() {
         let ignore_variant = quote!(__other(_serde::__private::de::Content<'de>),);
         let fallthrough = quote!(_serde::__private::Ok(__Field::__other(__value)));
-        (
-            Some(ignore_variant),
-            Some((fallthrough.clone(), fallthrough)),
-        )
+        (Some(ignore_variant), Some(fallthrough))
     } else if let Some(other_idx) = other_idx {
         let ignore_variant = fields[other_idx].1.clone();
         let fallthrough = quote!(_serde::__private::Ok(__Field::#ignore_variant));
-        (None, Some((fallthrough.clone(), fallthrough)))
+        (None, Some(fallthrough))
     } else if is_variant || cattrs.deny_unknown_fields() {
         (None, None)
     } else {
         let ignore_variant = quote!(__ignore,);
         let fallthrough = quote!(_serde::__private::Ok(__Field::__ignore));
-        (
-            Some(ignore_variant),
-            Some((fallthrough.clone(), fallthrough)),
-        )
+        (Some(ignore_variant), Some(fallthrough))
     };
 
     let visitor_impl = Stmts(deserialize_identifier(
@@ -1915,7 +1926,9 @@ fn deserialize_generated_identifier(
         fields,
         is_variant,
         fallthrough,
+        None,
         !is_variant && cattrs.has_flatten(),
+        None,
     ));
 
     let lifetime = if !is_variant && cattrs.has_flatten() {
@@ -1951,6 +1964,8 @@ fn deserialize_generated_identifier(
     }
 }
 
+// Generates `Deserialize::deserialize` body for an enum with
+// `serde(field_identifier)` or `serde(variant_identifier)` attribute.
 fn deserialize_custom_identifier(
     params: &Parameters,
     variants: &[Variant],
@@ -1965,32 +1980,38 @@ fn deserialize_custom_identifier(
     let this = &params.this;
     let this = quote!(#this);
 
-    let (ordinary, fallthrough) = if let Some(last) = variants.last() {
+    let (ordinary, fallthrough, fallthrough_borrowed) = if let Some(last) = variants.last() {
         let last_ident = &last.ident;
         if last.attrs.other() {
+            // Process `serde(other)` attribute. It would always be found on the
+            // last variant (checked in `check_identifier`), so all preceding
+            // are ordinary variants.
             let ordinary = &variants[..variants.len() - 1];
             let fallthrough = quote!(_serde::__private::Ok(#this::#last_ident));
-            (ordinary, Some((fallthrough.clone(), fallthrough)))
+            (ordinary, Some(fallthrough), None)
         } else if let Style::Newtype = last.style {
             let ordinary = &variants[..variants.len() - 1];
-            let fallthrough = |method| {
+            let fallthrough = |value| {
                 quote! {
                     _serde::__private::Result::map(
                         _serde::Deserialize::deserialize(
-                            _serde::__private::de::IdentifierDeserializer::#method(__value)
+                            _serde::__private::de::IdentifierDeserializer::from(#value)
                         ),
                         #this::#last_ident)
                 }
             };
             (
                 ordinary,
-                Some((fallthrough(quote!(from)), fallthrough(quote!(borrowed)))),
+                Some(fallthrough(quote!(__value))),
+                Some(fallthrough(quote!(_serde::__private::de::Borrowed(
+                    __value
+                )))),
             )
         } else {
-            (variants, None)
+            (variants, None, None)
         }
     } else {
-        (variants, None)
+        (variants, None, None)
     };
 
     let names_idents: Vec<_> = ordinary
@@ -2028,7 +2049,9 @@ fn deserialize_custom_identifier(
         &names_idents,
         is_variant,
         fallthrough,
+        fallthrough_borrowed,
         false,
+        cattrs.expecting(),
     ));
 
     quote_block! {
@@ -2057,13 +2080,14 @@ fn deserialize_identifier(
     this: &TokenStream,
     fields: &[(String, Ident, Vec<String>)],
     is_variant: bool,
-    // .0 for referenced data, .1 -- for borrowed
-    fallthrough: Option<(TokenStream, TokenStream)>,
+    fallthrough: Option<TokenStream>,
+    fallthrough_borrowed: Option<TokenStream>,
     collect_other_fields: bool,
+    expecting: Option<&str>,
 ) -> Fragment {
     let mut flat_fields = Vec::new();
     for (_, ident, aliases) in fields {
-        flat_fields.extend(aliases.iter().map(|alias| (alias, ident)))
+        flat_fields.extend(aliases.iter().map(|alias| (alias, ident)));
     }
 
     let field_strs: &Vec<_> = &flat_fields.iter().map(|(name, _)| name).collect();
@@ -2081,11 +2105,11 @@ fn deserialize_identifier(
         .map(|(_, ident, _)| quote!(#this::#ident))
         .collect();
 
-    let expecting = if is_variant {
+    let expecting = expecting.unwrap_or(if is_variant {
         "variant identifier"
     } else {
         "field identifier"
-    };
+    });
 
     let index_expecting = if is_variant { "variant" } else { "field" };
 
@@ -2121,22 +2145,36 @@ fn deserialize_identifier(
         (None, None, None, None)
     };
 
-    let (fallthrough_arm, fallthrough_borrowed_arm) = if let Some(fallthrough) = fallthrough {
+    let fallthrough_arm_tokens;
+    let fallthrough_arm = if let Some(fallthrough) = &fallthrough {
         fallthrough
     } else if is_variant {
-        let fallthrough = quote! {
+        fallthrough_arm_tokens = quote! {
             _serde::__private::Err(_serde::de::Error::unknown_variant(__value, VARIANTS))
         };
-        (fallthrough.clone(), fallthrough)
+        &fallthrough_arm_tokens
     } else {
-        let fallthrough = quote! {
+        fallthrough_arm_tokens = quote! {
             _serde::__private::Err(_serde::de::Error::unknown_field(__value, FIELDS))
         };
-        (fallthrough.clone(), fallthrough)
+        &fallthrough_arm_tokens
+    };
+
+    let u64_fallthrough_arm_tokens;
+    let u64_fallthrough_arm = if let Some(fallthrough) = &fallthrough {
+        fallthrough
+    } else {
+        let fallthrough_msg = format!("{} index 0 <= i < {}", index_expecting, fields.len());
+        u64_fallthrough_arm_tokens = quote! {
+            _serde::__private::Err(_serde::de::Error::invalid_value(
+                _serde::de::Unexpected::Unsigned(__value),
+                &#fallthrough_msg,
+            ))
+        };
+        &u64_fallthrough_arm_tokens
     };
 
     let variant_indices = 0_u64..;
-    let fallthrough_msg = format!("{} index 0 <= i < {}", index_expecting, fields.len());
     let visit_other = if collect_other_fields {
         quote! {
             fn visit_bool<__E>(self, __value: bool) -> _serde::__private::Result<Self::Value, __E>
@@ -2240,15 +2278,50 @@ fn deserialize_identifier(
                     #(
                         #variant_indices => _serde::__private::Ok(#main_constructors),
                     )*
-                    _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                        _serde::de::Unexpected::Unsigned(__value),
-                        &#fallthrough_msg,
-                    ))
+                    _ => #u64_fallthrough_arm,
                 }
             }
         }
     };
 
+    let visit_borrowed = if fallthrough_borrowed.is_some() || collect_other_fields {
+        let fallthrough_borrowed_arm = fallthrough_borrowed.as_ref().unwrap_or(fallthrough_arm);
+        Some(quote! {
+            fn visit_borrowed_str<__E>(self, __value: &'de str) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                match __value {
+                    #(
+                        #field_strs => _serde::__private::Ok(#constructors),
+                    )*
+                    _ => {
+                        #value_as_borrowed_str_content
+                        #fallthrough_borrowed_arm
+                    }
+                }
+            }
+
+            fn visit_borrowed_bytes<__E>(self, __value: &'de [u8]) -> _serde::__private::Result<Self::Value, __E>
+            where
+                __E: _serde::de::Error,
+            {
+                match __value {
+                    #(
+                        #field_bytes => _serde::__private::Ok(#constructors),
+                    )*
+                    _ => {
+                        #bytes_to_str
+                        #value_as_borrowed_bytes_content
+                        #fallthrough_borrowed_arm
+                    }
+                }
+            }
+        })
+    } else {
+        None
+    };
+
     quote_block! {
         fn expecting(&self, __formatter: &mut _serde::__private::Formatter) -> _serde::__private::fmt::Result {
             _serde::__private::Formatter::write_str(__formatter, #expecting)
@@ -2271,21 +2344,6 @@ fn deserialize_identifier(
             }
         }
 
-        fn visit_borrowed_str<__E>(self, __value: &'de str) -> _serde::__private::Result<Self::Value, __E>
-        where
-            __E: _serde::de::Error,
-        {
-            match __value {
-                #(
-                    #field_strs => _serde::__private::Ok(#constructors),
-                )*
-                _ => {
-                    #value_as_borrowed_str_content
-                    #fallthrough_borrowed_arm
-                }
-            }
-        }
-
         fn visit_bytes<__E>(self, __value: &[u8]) -> _serde::__private::Result<Self::Value, __E>
         where
             __E: _serde::de::Error,
@@ -2302,21 +2360,7 @@ fn deserialize_identifier(
             }
         }
 
-        fn visit_borrowed_bytes<__E>(self, __value: &'de [u8]) -> _serde::__private::Result<Self::Value, __E>
-        where
-            __E: _serde::de::Error,
-        {
-            match __value {
-                #(
-                    #field_bytes => _serde::__private::Ok(#constructors),
-                )*
-                _ => {
-                    #bytes_to_str
-                    #value_as_borrowed_bytes_content
-                    #fallthrough_borrowed_arm
-                }
-            }
-        }
+        #visit_borrowed
     }
 }
 

serde_derive/src/dummy.rs

@@ -23,7 +23,7 @@ pub fn wrap_in_const(
             use #path as _serde;
         },
         None => quote! {
-            #[allow(rust_2018_idioms, clippy::useless_attribute)]
+            #[allow(unused_extern_crates, clippy::useless_attribute)]
             extern crate serde as _serde;
         },
     };

serde_derive/src/internals/ast.rs

@@ -23,7 +23,7 @@ pub struct Container<'a> {
 
 /// The fields of a struct or enum.
 ///
-/// Analagous to `syn::Data`.
+/// Analogous to `syn::Data`.
 pub enum Data<'a> {
     Enum(Vec<Variant<'a>>),
     Struct(Style, Vec<Field<'a>>),

serde_derive/src/internals/attr.rs

@@ -1,10 +1,10 @@
+use internals::respan::respan;
 use internals::symbol::*;
 use internals::{ungroup, Ctxt};
-use proc_macro2::{Group, Span, TokenStream, TokenTree};
+use proc_macro2::{Spacing, Span, TokenStream, TokenTree};
 use quote::ToTokens;
 use std::borrow::Cow;
 use std::collections::BTreeSet;
-use std::str::FromStr;
 use syn;
 use syn::parse::{self, Parse, ParseStream};
 use syn::punctuated::Punctuated;
@@ -223,6 +223,8 @@ pub struct Container {
     has_flatten: bool,
     serde_path: Option<syn::Path>,
     is_packed: bool,
+    /// Error message generated when type can't be deserialized
+    expecting: Option<String>,
 }
 
 /// Styles of representing an enum.
@@ -305,6 +307,7 @@ impl Container {
         let mut field_identifier = BoolAttr::none(cx, FIELD_IDENTIFIER);
         let mut variant_identifier = BoolAttr::none(cx, VARIANT_IDENTIFIER);
         let mut serde_path = Attr::none(cx, CRATE);
+        let mut expecting = Attr::none(cx, EXPECTING);
 
         for meta_item in item
             .attrs
@@ -337,13 +340,7 @@ impl Container {
                                 rename_all_ser_rule.set(&m.path, rename_rule);
                                 rename_all_de_rule.set(&m.path, rename_rule);
                             }
-                            Err(()) => cx.error_spanned_by(
-                                s,
-                                format!(
-                                    "unknown rename rule for #[serde(rename_all = {:?})]",
-                                    s.value(),
-                                ),
-                            ),
+                            Err(err) => cx.error_spanned_by(s, err),
                         }
                     }
                 }
@@ -354,25 +351,13 @@ impl Container {
                         if let Some(ser) = ser {
                             match RenameRule::from_str(&ser.value()) {
                                 Ok(rename_rule) => rename_all_ser_rule.set(&m.path, rename_rule),
-                                Err(()) => cx.error_spanned_by(
-                                    ser,
-                                    format!(
-                                        "unknown rename rule for #[serde(rename_all = {:?})]",
-                                        ser.value(),
-                                    ),
-                                ),
+                                Err(err) => cx.error_spanned_by(ser, err),
                             }
                         }
                         if let Some(de) = de {
                             match RenameRule::from_str(&de.value()) {
                                 Ok(rename_rule) => rename_all_de_rule.set(&m.path, rename_rule),
-                                Err(()) => cx.error_spanned_by(
-                                    de,
-                                    format!(
-                                        "unknown rename rule for #[serde(rename_all = {:?})]",
-                                        de.value(),
-                                    ),
-                                ),
+                                Err(err) => cx.error_spanned_by(de, err),
                             }
                         }
                     }
@@ -571,7 +556,14 @@ impl Container {
                 // Parse `#[serde(crate = "foo")]`
                 Meta(NameValue(m)) if m.path == CRATE => {
                     if let Ok(path) = parse_lit_into_path(cx, CRATE, &m.lit) {
-                        serde_path.set(&m.path, path)
+                        serde_path.set(&m.path, path);
+                    }
+                }
+
+                // Parse `#[serde(expecting = "a message")]`
+                Meta(NameValue(m)) if m.path == EXPECTING => {
+                    if let Ok(s) = get_lit_str(cx, EXPECTING, &m.lit) {
+                        expecting.set(&m.path, s.value());
                     }
                 }
 
@@ -627,6 +619,7 @@ impl Container {
             has_flatten: false,
             serde_path: serde_path.get(),
             is_packed,
+            expecting: expecting.get(),
         }
     }
 
@@ -702,6 +695,12 @@ impl Container {
         self.custom_serde_path()
             .map_or_else(|| Cow::Owned(parse_quote!(_serde)), Cow::Borrowed)
     }
+
+    /// Error message generated when type can't be deserialized.
+    /// If `None`, default message will be used
+    pub fn expecting(&self) -> Option<&str> {
+        self.expecting.as_ref().map(String::as_ref)
+    }
 }
 
 fn decide_tag(
@@ -914,13 +913,7 @@ impl Variant {
                                 rename_all_ser_rule.set(&m.path, rename_rule);
                                 rename_all_de_rule.set(&m.path, rename_rule);
                             }
-                            Err(()) => cx.error_spanned_by(
-                                s,
-                                format!(
-                                    "unknown rename rule for #[serde(rename_all = {:?})]",
-                                    s.value()
-                                ),
-                            ),
+                            Err(err) => cx.error_spanned_by(s, err),
                         }
                     }
                 }
@@ -931,25 +924,13 @@ impl Variant {
                         if let Some(ser) = ser {
                             match RenameRule::from_str(&ser.value()) {
                                 Ok(rename_rule) => rename_all_ser_rule.set(&m.path, rename_rule),
-                                Err(()) => cx.error_spanned_by(
-                                    ser,
-                                    format!(
-                                        "unknown rename rule for #[serde(rename_all = {:?})]",
-                                        ser.value(),
-                                    ),
-                                ),
+                                Err(err) => cx.error_spanned_by(ser, err),
                             }
                         }
                         if let Some(de) = de {
                             match RenameRule::from_str(&de.value()) {
                                 Ok(rename_rule) => rename_all_de_rule.set(&m.path, rename_rule),
-                                Err(()) => cx.error_spanned_by(
-                                    de,
-                                    format!(
-                                        "unknown rename rule for #[serde(rename_all = {:?})]",
-                                        de.value(),
-                                    ),
-                                ),
+                                Err(err) => cx.error_spanned_by(de, err),
                             }
                         }
                     }
@@ -1628,7 +1609,7 @@ fn get_lit_str2<'a>(
 fn parse_lit_into_path(cx: &Ctxt, attr_name: Symbol, lit: &syn::Lit) -> Result<syn::Path, ()> {
     let string = get_lit_str(cx, attr_name, lit)?;
     parse_lit_str(string).map_err(|_| {
-        cx.error_spanned_by(lit, format!("failed to parse path: {:?}", string.value()))
+        cx.error_spanned_by(lit, format!("failed to parse path: {:?}", string.value()));
     })
 }
 
@@ -1639,7 +1620,7 @@ fn parse_lit_into_expr_path(
 ) -> Result<syn::ExprPath, ()> {
     let string = get_lit_str(cx, attr_name, lit)?;
     parse_lit_str(string).map_err(|_| {
-        cx.error_spanned_by(lit, format!("failed to parse path: {:?}", string.value()))
+        cx.error_spanned_by(lit, format!("failed to parse path: {:?}", string.value()));
     })
 }
 
@@ -1668,7 +1649,7 @@ fn parse_lit_into_ty(cx: &Ctxt, attr_name: Symbol, lit: &syn::Lit) -> Result<syn
         cx.error_spanned_by(
             lit,
             format!("failed to parse type: {} = {:?}", attr_name, string.value()),
-        )
+        );
     })
 }
 
@@ -1921,14 +1902,41 @@ fn collect_lifetimes(ty: &syn::Type, out: &mut BTreeSet<syn::Lifetime>) {
         syn::Type::Group(ty) => {
             collect_lifetimes(&ty.elem, out);
         }
+        syn::Type::Macro(ty) => {
+            collect_lifetimes_from_tokens(ty.mac.tokens.clone(), out);
+        }
         syn::Type::BareFn(_)
         | syn::Type::Never(_)
         | syn::Type::TraitObject(_)
         | syn::Type::ImplTrait(_)
         | syn::Type::Infer(_)
-        | syn::Type::Macro(_)
-        | syn::Type::Verbatim(_)
-        | _ => {}
+        | syn::Type::Verbatim(_) => {}
+
+        #[cfg(test)]
+        syn::Type::__TestExhaustive(_) => unimplemented!(),
+        #[cfg(not(test))]
+        _ => {}
+    }
+}
+
+fn collect_lifetimes_from_tokens(tokens: TokenStream, out: &mut BTreeSet<syn::Lifetime>) {
+    let mut iter = tokens.into_iter();
+    while let Some(tt) = iter.next() {
+        match &tt {
+            TokenTree::Punct(op) if op.as_char() == '\'' && op.spacing() == Spacing::Joint => {
+                if let Some(TokenTree::Ident(ident)) = iter.next() {
+                    out.insert(syn::Lifetime {
+                        apostrophe: op.span(),
+                        ident,
+                    });
+                }
+            }
+            TokenTree::Group(group) => {
+                let tokens = group.stream();
+                collect_lifetimes_from_tokens(tokens, out);
+            }
+            _ => {}
+        }
     }
 }
 
@@ -1942,20 +1950,5 @@ where
 
 fn spanned_tokens(s: &syn::LitStr) -> parse::Result<TokenStream> {
     let stream = syn::parse_str(&s.value())?;
-    Ok(respan_token_stream(stream, s.span()))
-}
-
-fn respan_token_stream(stream: TokenStream, span: Span) -> TokenStream {
-    stream
-        .into_iter()
-        .map(|token| respan_token_tree(token, span))
-        .collect()
-}
-
-fn respan_token_tree(mut token: TokenTree, span: Span) -> TokenTree {
-    if let TokenTree::Group(g) = &mut token {
-        *g = Group::new(g.delimiter(), respan_token_stream(g.stream(), span));
-    }
-    token.set_span(span);
-    token
+    Ok(respan(stream, s.span()))
 }

serde_derive/src/internals/case.rs

@@ -5,7 +5,7 @@
 #[allow(deprecated, unused_imports)]
 use std::ascii::AsciiExt;
 
-use std::str::FromStr;
+use std::fmt::{self, Debug, Display};
 
 use self::RenameRule::*;
 
@@ -17,7 +17,7 @@ pub enum RenameRule {
     /// Rename direct children to "lowercase" style.
     LowerCase,
     /// Rename direct children to "UPPERCASE" style.
-    UPPERCASE,
+    UpperCase,
     /// Rename direct children to "PascalCase" style, as typically used for
     /// enum variants.
     PascalCase,
@@ -35,13 +35,35 @@ pub enum RenameRule {
     ScreamingKebabCase,
 }
 
+static RENAME_RULES: &[(&str, RenameRule)] = &[
+    ("lowercase", LowerCase),
+    ("UPPERCASE", UpperCase),
+    ("PascalCase", PascalCase),
+    ("camelCase", CamelCase),
+    ("snake_case", SnakeCase),
+    ("SCREAMING_SNAKE_CASE", ScreamingSnakeCase),
+    ("kebab-case", KebabCase),
+    ("SCREAMING-KEBAB-CASE", ScreamingKebabCase),
+];
+
 impl RenameRule {
+    pub fn from_str(rename_all_str: &str) -> Result<Self, ParseError> {
+        for (name, rule) in RENAME_RULES {
+            if rename_all_str == *name {
+                return Ok(*rule);
+            }
+        }
+        Err(ParseError {
+            unknown: rename_all_str,
+        })
+    }
+
     /// Apply a renaming rule to an enum variant, returning the version expected in the source.
     pub fn apply_to_variant(&self, variant: &str) -> String {
         match *self {
             None | PascalCase => variant.to_owned(),
             LowerCase => variant.to_ascii_lowercase(),
-            UPPERCASE => variant.to_ascii_uppercase(),
+            UpperCase => variant.to_ascii_uppercase(),
             CamelCase => variant[..1].to_ascii_lowercase() + &variant[1..],
             SnakeCase => {
                 let mut snake = String::new();
@@ -65,7 +87,7 @@ impl RenameRule {
     pub fn apply_to_field(&self, field: &str) -> String {
         match *self {
             None | LowerCase | SnakeCase => field.to_owned(),
-            UPPERCASE => field.to_ascii_uppercase(),
+            UpperCase => field.to_ascii_uppercase(),
             PascalCase => {
                 let mut pascal = String::new();
                 let mut capitalize = true;
@@ -92,21 +114,22 @@ impl RenameRule {
     }
 }
 
-impl FromStr for RenameRule {
-    type Err = ();
+pub struct ParseError<'a> {
+    unknown: &'a str,
+}
 
-    fn from_str(rename_all_str: &str) -> Result<Self, Self::Err> {
-        match rename_all_str {
-            "lowercase" => Ok(LowerCase),
-            "UPPERCASE" => Ok(UPPERCASE),
-            "PascalCase" => Ok(PascalCase),
-            "camelCase" => Ok(CamelCase),
-            "snake_case" => Ok(SnakeCase),
-            "SCREAMING_SNAKE_CASE" => Ok(ScreamingSnakeCase),
-            "kebab-case" => Ok(KebabCase),
-            "SCREAMING-KEBAB-CASE" => Ok(ScreamingKebabCase),
-            _ => Err(()),
+impl<'a> Display for ParseError<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("unknown rename rule `rename_all = ")?;
+        Debug::fmt(self.unknown, f)?;
+        f.write_str("`, expected one of ")?;
+        for (i, (name, _rule)) in RENAME_RULES.iter().enumerate() {
+            if i > 0 {
+                f.write_str(", ")?;
+            }
+            Debug::fmt(name, f)?;
         }
+        Ok(())
     }
 }
 
@@ -131,7 +154,7 @@ fn rename_variants() {
     ] {
         assert_eq!(None.apply_to_variant(original), original);
         assert_eq!(LowerCase.apply_to_variant(original), lower);
-        assert_eq!(UPPERCASE.apply_to_variant(original), upper);
+        assert_eq!(UpperCase.apply_to_variant(original), upper);
         assert_eq!(PascalCase.apply_to_variant(original), original);
         assert_eq!(CamelCase.apply_to_variant(original), camel);
         assert_eq!(SnakeCase.apply_to_variant(original), snake);
@@ -163,7 +186,7 @@ fn rename_fields() {
         ("z42", "Z42", "Z42", "z42", "Z42", "z42", "Z42"),
     ] {
         assert_eq!(None.apply_to_field(original), original);
-        assert_eq!(UPPERCASE.apply_to_field(original), upper);
+        assert_eq!(UpperCase.apply_to_field(original), upper);
         assert_eq!(PascalCase.apply_to_field(original), pascal);
         assert_eq!(CamelCase.apply_to_field(original), camel);
         assert_eq!(SnakeCase.apply_to_field(original), original);

serde_derive/src/internals/check.rs

@@ -260,7 +260,7 @@ fn check_internal_tag_field_name_conflict(cx: &Ctxt, cont: &Container) {
         cx.error_spanned_by(
             cont.original,
             format!("variant field name `{}` conflicts with internal tag", tag),
-        )
+        );
     };
 
     for variant in variants {
@@ -396,7 +396,7 @@ fn member_message(member: &Member) -> String {
 }
 
 fn allow_transparent(field: &Field, derive: Derive) -> bool {
-    if let Type::Path(ty) = ungroup(&field.ty) {
+    if let Type::Path(ty) = ungroup(field.ty) {
         if let Some(seg) = ty.path.segments.last() {
             if seg.ident == "PhantomData" {
                 return false;

serde_derive/src/internals/mod.rs

@@ -4,8 +4,12 @@ pub mod attr;
 mod ctxt;
 pub use self::ctxt::Ctxt;
 
+mod receiver;
+pub use self::receiver::replace_receiver;
+
 mod case;
 mod check;
+mod respan;
 mod symbol;
 
 use syn::Type;

serde_derive/src/internals/receiver.rs

@@ -0,0 +1,287 @@
+use internals::respan::respan;
+use proc_macro2::Span;
+use quote::ToTokens;
+use std::mem;
+use syn::punctuated::Punctuated;
+use syn::{
+    parse_quote, Data, DeriveInput, Expr, ExprPath, GenericArgument, GenericParam, Generics, Macro,
+    Path, PathArguments, QSelf, ReturnType, Type, TypeParamBound, TypePath, WherePredicate,
+};
+
+pub fn replace_receiver(input: &mut DeriveInput) {
+    let self_ty = {
+        let ident = &input.ident;
+        let ty_generics = input.generics.split_for_impl().1;
+        parse_quote!(#ident #ty_generics)
+    };
+    let mut visitor = ReplaceReceiver(&self_ty);
+    visitor.visit_generics_mut(&mut input.generics);
+    visitor.visit_data_mut(&mut input.data);
+}
+
+struct ReplaceReceiver<'a>(&'a TypePath);
+
+impl ReplaceReceiver<'_> {
+    fn self_ty(&self, span: Span) -> TypePath {
+        let tokens = self.0.to_token_stream();
+        let respanned = respan(tokens, span);
+        syn::parse2(respanned).unwrap()
+    }
+
+    fn self_to_qself(&self, qself: &mut Option<QSelf>, path: &mut Path) {
+        if path.leading_colon.is_some() || path.segments[0].ident != "Self" {
+            return;
+        }
+
+        if path.segments.len() == 1 {
+            self.self_to_expr_path(path);
+            return;
+        }
+
+        let span = path.segments[0].ident.span();
+        *qself = Some(QSelf {
+            lt_token: Token![<](span),
+            ty: Box::new(Type::Path(self.self_ty(span))),
+            position: 0,
+            as_token: None,
+            gt_token: Token![>](span),
+        });
+
+        path.leading_colon = Some(**path.segments.pairs().next().unwrap().punct().unwrap());
+
+        let segments = mem::replace(&mut path.segments, Punctuated::new());
+        path.segments = segments.into_pairs().skip(1).collect();
+    }
+
+    fn self_to_expr_path(&self, path: &mut Path) {
+        let self_ty = self.self_ty(path.segments[0].ident.span());
+        let variant = mem::replace(path, self_ty.path);
+        for segment in &mut path.segments {
+            if let PathArguments::AngleBracketed(bracketed) = &mut segment.arguments {
+                if bracketed.colon2_token.is_none() && !bracketed.args.is_empty() {
+                    bracketed.colon2_token = Some(<Token![::]>::default());
+                }
+            }
+        }
+        if variant.segments.len() > 1 {
+            path.segments.push_punct(<Token![::]>::default());
+            path.segments.extend(variant.segments.into_pairs().skip(1));
+        }
+    }
+}
+
+impl ReplaceReceiver<'_> {
+    // `Self` -> `Receiver`
+    fn visit_type_mut(&mut self, ty: &mut Type) {
+        let span = if let Type::Path(node) = ty {
+            if node.qself.is_none() && node.path.is_ident("Self") {
+                node.path.segments[0].ident.span()
+            } else {
+                self.visit_type_path_mut(node);
+                return;
+            }
+        } else {
+            self.visit_type_mut_impl(ty);
+            return;
+        };
+        *ty = self.self_ty(span).into();
+    }
+
+    // `Self::Assoc` -> `<Receiver>::Assoc`
+    fn visit_type_path_mut(&mut self, ty: &mut TypePath) {
+        if ty.qself.is_none() {
+            self.self_to_qself(&mut ty.qself, &mut ty.path);
+        }
+        self.visit_type_path_mut_impl(ty);
+    }
+
+    // `Self::method` -> `<Receiver>::method`
+    fn visit_expr_path_mut(&mut self, expr: &mut ExprPath) {
+        if expr.qself.is_none() {
+            self.self_to_qself(&mut expr.qself, &mut expr.path);
+        }
+        self.visit_expr_path_mut_impl(expr);
+    }
+
+    // Everything below is simply traversing the syntax tree.
+
+    fn visit_type_mut_impl(&mut self, ty: &mut Type) {
+        match ty {
+            Type::Array(ty) => {
+                self.visit_type_mut(&mut ty.elem);
+                self.visit_expr_mut(&mut ty.len);
+            }
+            Type::BareFn(ty) => {
+                for arg in &mut ty.inputs {
+                    self.visit_type_mut(&mut arg.ty);
+                }
+                self.visit_return_type_mut(&mut ty.output);
+            }
+            Type::Group(ty) => self.visit_type_mut(&mut ty.elem),
+            Type::ImplTrait(ty) => {
+                for bound in &mut ty.bounds {
+                    self.visit_type_param_bound_mut(bound);
+                }
+            }
+            Type::Macro(ty) => self.visit_macro_mut(&mut ty.mac),
+            Type::Paren(ty) => self.visit_type_mut(&mut ty.elem),
+            Type::Path(ty) => {
+                if let Some(qself) = &mut ty.qself {
+                    self.visit_type_mut(&mut qself.ty);
+                }
+                self.visit_path_mut(&mut ty.path);
+            }
+            Type::Ptr(ty) => self.visit_type_mut(&mut ty.elem),
+            Type::Reference(ty) => self.visit_type_mut(&mut ty.elem),
+            Type::Slice(ty) => self.visit_type_mut(&mut ty.elem),
+            Type::TraitObject(ty) => {
+                for bound in &mut ty.bounds {
+                    self.visit_type_param_bound_mut(bound);
+                }
+            }
+            Type::Tuple(ty) => {
+                for elem in &mut ty.elems {
+                    self.visit_type_mut(elem);
+                }
+            }
+
+            Type::Infer(_) | Type::Never(_) | Type::Verbatim(_) => {}
+
+            #[cfg(test)]
+            Type::__TestExhaustive(_) => unimplemented!(),
+            #[cfg(not(test))]
+            _ => {}
+        }
+    }
+
+    fn visit_type_path_mut_impl(&mut self, ty: &mut TypePath) {
+        if let Some(qself) = &mut ty.qself {
+            self.visit_type_mut(&mut qself.ty);
+        }
+        self.visit_path_mut(&mut ty.path);
+    }
+
+    fn visit_expr_path_mut_impl(&mut self, expr: &mut ExprPath) {
+        if let Some(qself) = &mut expr.qself {
+            self.visit_type_mut(&mut qself.ty);
+        }
+        self.visit_path_mut(&mut expr.path);
+    }
+
+    fn visit_path_mut(&mut self, path: &mut Path) {
+        for segment in &mut path.segments {
+            self.visit_path_arguments_mut(&mut segment.arguments);
+        }
+    }
+
+    fn visit_path_arguments_mut(&mut self, arguments: &mut PathArguments) {
+        match arguments {
+            PathArguments::None => {}
+            PathArguments::AngleBracketed(arguments) => {
+                for arg in &mut arguments.args {
+                    match arg {
+                        GenericArgument::Type(arg) => self.visit_type_mut(arg),
+                        GenericArgument::Binding(arg) => self.visit_type_mut(&mut arg.ty),
+                        GenericArgument::Lifetime(_)
+                        | GenericArgument::Constraint(_)
+                        | GenericArgument::Const(_) => {}
+                    }
+                }
+            }
+            PathArguments::Parenthesized(arguments) => {
+                for argument in &mut arguments.inputs {
+                    self.visit_type_mut(argument);
+                }
+                self.visit_return_type_mut(&mut arguments.output);
+            }
+        }
+    }
+
+    fn visit_return_type_mut(&mut self, return_type: &mut ReturnType) {
+        match return_type {
+            ReturnType::Default => {}
+            ReturnType::Type(_, output) => self.visit_type_mut(output),
+        }
+    }
+
+    fn visit_type_param_bound_mut(&mut self, bound: &mut TypeParamBound) {
+        match bound {
+            TypeParamBound::Trait(bound) => self.visit_path_mut(&mut bound.path),
+            TypeParamBound::Lifetime(_) => {}
+        }
+    }
+
+    fn visit_generics_mut(&mut self, generics: &mut Generics) {
+        for param in &mut generics.params {
+            match param {
+                GenericParam::Type(param) => {
+                    for bound in &mut param.bounds {
+                        self.visit_type_param_bound_mut(bound);
+                    }
+                }
+                GenericParam::Lifetime(_) | GenericParam::Const(_) => {}
+            }
+        }
+        if let Some(where_clause) = &mut generics.where_clause {
+            for predicate in &mut where_clause.predicates {
+                match predicate {
+                    WherePredicate::Type(predicate) => {
+                        self.visit_type_mut(&mut predicate.bounded_ty);
+                        for bound in &mut predicate.bounds {
+                            self.visit_type_param_bound_mut(bound);
+                        }
+                    }
+                    WherePredicate::Lifetime(_) | WherePredicate::Eq(_) => {}
+                }
+            }
+        }
+    }
+
+    fn visit_data_mut(&mut self, data: &mut Data) {
+        match data {
+            Data::Struct(data) => {
+                for field in &mut data.fields {
+                    self.visit_type_mut(&mut field.ty);
+                }
+            }
+            Data::Enum(data) => {
+                for variant in &mut data.variants {
+                    for field in &mut variant.fields {
+                        self.visit_type_mut(&mut field.ty);
+                    }
+                }
+            }
+            Data::Union(_) => {}
+        }
+    }
+
+    fn visit_expr_mut(&mut self, expr: &mut Expr) {
+        match expr {
+            Expr::Binary(expr) => {
+                self.visit_expr_mut(&mut expr.left);
+                self.visit_expr_mut(&mut expr.right);
+            }
+            Expr::Call(expr) => {
+                self.visit_expr_mut(&mut expr.func);
+                for arg in &mut expr.args {
+                    self.visit_expr_mut(arg);
+                }
+            }
+            Expr::Cast(expr) => {
+                self.visit_expr_mut(&mut expr.expr);
+                self.visit_type_mut(&mut expr.ty);
+            }
+            Expr::Field(expr) => self.visit_expr_mut(&mut expr.base),
+            Expr::Index(expr) => {
+                self.visit_expr_mut(&mut expr.expr);
+                self.visit_expr_mut(&mut expr.index);
+            }
+            Expr::Paren(expr) => self.visit_expr_mut(&mut expr.expr),
+            Expr::Path(expr) => self.visit_expr_path_mut(expr),
+            Expr::Unary(expr) => self.visit_expr_mut(&mut expr.expr),
+            _ => {}
+        }
+    }
+
+    fn visit_macro_mut(&mut self, _mac: &mut Macro) {}
+}

serde_derive/src/internals/respan.rs

@@ -0,0 +1,16 @@
+use proc_macro2::{Group, Span, TokenStream, TokenTree};
+
+pub(crate) fn respan(stream: TokenStream, span: Span) -> TokenStream {
+    stream
+        .into_iter()
+        .map(|token| respan_token(token, span))
+        .collect()
+}
+
+fn respan_token(mut token: TokenTree, span: Span) -> TokenTree {
+    if let TokenTree::Group(g) = &mut token {
+        *g = Group::new(g.delimiter(), respan(g.stream(), span));
+    }
+    token.set_span(span);
+    token
+}

serde_derive/src/internals/symbol.rs

@@ -35,6 +35,7 @@ pub const TRY_FROM: Symbol = Symbol("try_from");
 pub const UNTAGGED: Symbol = Symbol("untagged");
 pub const VARIANT_IDENTIFIER: Symbol = Symbol("variant_identifier");
 pub const WITH: Symbol = Symbol("with");
+pub const EXPECTING: Symbol = Symbol("expecting");
 
 impl PartialEq<Symbol> for Ident {
     fn eq(&self, word: &Symbol) -> bool {

serde_derive/src/lib.rs

@@ -13,13 +13,19 @@
 //!
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html
 
-#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.121")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.128")]
 #![allow(unknown_lints, bare_trait_objects)]
 #![deny(clippy::all, clippy::pedantic)]
 // Ignored clippy lints
 #![allow(
+    // clippy false positive: https://github.com/rust-lang/rust-clippy/issues/7054
+    clippy::branches_sharing_code,
     clippy::cognitive_complexity,
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/7575
+    clippy::collapsible_match,
     clippy::enum_variant_names,
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/6797
+    clippy::manual_map,
     clippy::match_like_matches_macro,
     clippy::needless_pass_by_value,
     clippy::too_many_arguments,
@@ -35,11 +41,13 @@
     clippy::checked_conversions,
     clippy::doc_markdown,
     clippy::enum_glob_use,
-    clippy::filter_map,
     clippy::indexing_slicing,
     clippy::items_after_statements,
+    clippy::let_underscore_drop,
     clippy::map_err_ignore,
     clippy::match_same_arms,
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/6984
+    clippy::match_wildcard_for_single_variants,
     clippy::module_name_repetitions,
     clippy::must_use_candidate,
     clippy::option_if_let_else,
@@ -48,6 +56,7 @@
     clippy::struct_excessive_bools,
     clippy::too_many_lines,
     clippy::unseparated_literal_suffix,
+    clippy::unused_self,
     clippy::use_self,
     clippy::wildcard_imports
 )]
@@ -78,16 +87,16 @@ mod try;
 
 #[proc_macro_derive(Serialize, attributes(serde))]
 pub fn derive_serialize(input: TokenStream) -> TokenStream {
-    let input = parse_macro_input!(input as DeriveInput);
-    ser::expand_derive_serialize(&input)
+    let mut input = parse_macro_input!(input as DeriveInput);
+    ser::expand_derive_serialize(&mut input)
         .unwrap_or_else(to_compile_errors)
         .into()
 }
 
 #[proc_macro_derive(Deserialize, attributes(serde))]
 pub fn derive_deserialize(input: TokenStream) -> TokenStream {
-    let input = parse_macro_input!(input as DeriveInput);
-    de::expand_derive_deserialize(&input)
+    let mut input = parse_macro_input!(input as DeriveInput);
+    de::expand_derive_deserialize(&mut input)
         .unwrap_or_else(to_compile_errors)
         .into()
 }

serde_derive/src/ser.rs

@@ -6,10 +6,14 @@ use bound;
 use dummy;
 use fragment::{Fragment, Match, Stmts};
 use internals::ast::{Container, Data, Field, Style, Variant};
-use internals::{attr, Ctxt, Derive};
+use internals::{attr, replace_receiver, Ctxt, Derive};
 use pretend;
 
-pub fn expand_derive_serialize(input: &syn::DeriveInput) -> Result<TokenStream, Vec<syn::Error>> {
+pub fn expand_derive_serialize(
+    input: &mut syn::DeriveInput,
+) -> Result<TokenStream, Vec<syn::Error>> {
+    replace_receiver(input);
+
     let ctxt = Ctxt::new();
     let cont = match Container::from_ast(&ctxt, input, Derive::Serialize) {
         Some(cont) => cont,
@@ -1095,7 +1099,7 @@ fn serialize_struct_visitor(
             let mut field_expr = if is_enum {
                 quote!(#member)
             } else {
-                get_member(params, field, &member)
+                get_member(params, field, member)
             };
 
             let key_expr = field.attrs.name().serialize_name();

serde_derive_internals/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive_internals"
-version = "0.25.0" # remember to update html_root_url
+version = "0.26.0" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "AST representation used by Serde derive macros. Unstable."
@@ -16,7 +16,7 @@ path = "lib.rs"
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "1.0.33", default-features = false, features = ["derive", "parsing", "printing", "clone-impls"] }
+syn = { version = "1.0.60", default-features = false, features = ["derive", "parsing", "printing", "clone-impls"] }
 
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]

serde_derive_internals/build.rs

@@ -0,0 +1,12 @@
+use std::path::Path;
+
+fn main() {
+    // Sometimes on Windows the git checkout does not correctly wire up the
+    // symlink from serde_derive_internals/src to serde_derive/src/internals.
+    // When this happens we'll just build based on relative paths within the git
+    // repo.
+    let mod_behind_symlink = Path::new("src/mod.rs");
+    if !mod_behind_symlink.exists() {
+        println!("cargo:rustc-cfg=serde_build_from_git");
+    }
+}

serde_derive_internals/lib.rs

@@ -1,17 +1,39 @@
-#![doc(html_root_url = "https://docs.rs/serde_derive_internals/0.25.0")]
+#![doc(html_root_url = "https://docs.rs/serde_derive_internals/0.26.0")]
 #![allow(unknown_lints, bare_trait_objects)]
-#![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
-#![cfg_attr(
-    feature = "cargo-clippy",
-    allow(
-        cognitive_complexity,
-        redundant_field_names,
-        result_unit_err,
-        trivially_copy_pass_by_ref,
-        wildcard_in_or_patterns,
-        // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704
-        unnested_or_patterns,
-    )
+#![deny(clippy::all, clippy::pedantic)]
+// Ignored clippy lints
+#![allow(
+    clippy::cognitive_complexity,
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/7575
+    clippy::collapsible_match,
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/6797
+    clippy::manual_map,
+    clippy::missing_panics_doc,
+    clippy::redundant_field_names,
+    clippy::result_unit_err,
+    clippy::should_implement_trait,
+    clippy::trivially_copy_pass_by_ref,
+    clippy::wildcard_in_or_patterns,
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/5704
+    clippy::unnested_or_patterns,
+)]
+// Ignored clippy_pedantic lints
+#![allow(
+    clippy::doc_markdown,
+    clippy::enum_glob_use,
+    clippy::items_after_statements,
+    clippy::let_underscore_drop,
+    clippy::match_same_arms,
+    // clippy bug: https://github.com/rust-lang/rust-clippy/issues/6984
+    clippy::match_wildcard_for_single_variants,
+    clippy::missing_errors_doc,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::similar_names,
+    clippy::struct_excessive_bools,
+    clippy::too_many_lines,
+    clippy::unused_self,
+    clippy::wildcard_imports
 )]
 
 #[macro_use]
@@ -20,7 +42,8 @@ extern crate syn;
 extern crate proc_macro2;
 extern crate quote;
 
-#[path = "src/mod.rs"]
+#[cfg_attr(serde_build_from_git, path = "../serde_derive/src/internals/mod.rs")]
+#[cfg_attr(not(serde_build_from_git), path = "src/mod.rs")]
 mod internals;
 
 pub use internals::*;

serde_test/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_test"
-version = "1.0.121" # remember to update html_root_url
+version = "1.0.128" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "Token De/Serializer for testing De/Serialize implementations"

serde_test/build.rs

@@ -0,0 +1,30 @@
+use std::env;
+use std::process::Command;
+use std::str;
+
+// The rustc-cfg strings below are *not* public API. Please let us know by
+// opening a GitHub issue if your build environment requires some way to enable
+// these cfgs other than by executing our build script.
+fn main() {
+    let minor = match rustc_minor_version() {
+        Some(minor) => minor,
+        None => return,
+    };
+
+    // #[track_caller] stabilized in Rust 1.46:
+    // https://blog.rust-lang.org/2020/08/27/Rust-1.46.0.html#track_caller
+    if minor >= 46 {
+        println!("cargo:rustc-cfg=track_caller");
+    }
+}
+
+fn rustc_minor_version() -> Option<u32> {
+    let rustc = env::var_os("RUSTC")?;
+    let output = Command::new(rustc).arg("--version").output().ok()?;
+    let version = str::from_utf8(&output.stdout).ok()?;
+    let mut pieces = version.split('.');
+    if pieces.next() != Some("rustc 1") {
+        return None;
+    }
+    pieces.next()?.parse().ok()
+}

serde_test/src/assert.rs

@@ -28,6 +28,7 @@ use std::fmt::Debug;
 ///     Token::StructEnd,
 /// ]);
 /// ```
+#[cfg_attr(track_caller, track_caller)]
 pub fn assert_tokens<'de, T>(value: &T, tokens: &'de [Token])
 where
     T: Serialize + Deserialize<'de> + PartialEq + Debug,
@@ -58,6 +59,7 @@ where
 ///     Token::StructEnd,
 /// ]);
 /// ```
+#[cfg_attr(track_caller, track_caller)]
 pub fn assert_ser_tokens<T>(value: &T, tokens: &[Token])
 where
     T: Serialize,
@@ -110,6 +112,7 @@ where
 ///     assert_ser_tokens_error(&example, expected, error);
 /// }
 /// ```
+#[cfg_attr(track_caller, track_caller)]
 pub fn assert_ser_tokens_error<T>(value: &T, tokens: &[Token], error: &str)
 where
     T: Serialize,
@@ -147,6 +150,7 @@ where
 ///     Token::StructEnd,
 /// ]);
 /// ```
+#[cfg_attr(track_caller, track_caller)]
 pub fn assert_de_tokens<'de, T>(value: &T, tokens: &'de [Token])
 where
     T: Deserialize<'de> + PartialEq + Debug,
@@ -199,6 +203,7 @@ where
 ///     "unknown field `x`, expected `a` or `b`",
 /// );
 /// ```
+#[cfg_attr(track_caller, track_caller)]
 pub fn assert_de_tokens_error<'de, T>(tokens: &'de [Token], error: &str)
 where
     T: Deserialize<'de>,

serde_test/src/configure.rs

@@ -777,6 +777,17 @@ macro_rules! impl_deserializer {
             {
                 self.0.next_value_seed($wrapper(seed))
             }
+            fn next_entry_seed<K, V>(
+                &mut self,
+                kseed: K,
+                vseed: V,
+            ) -> Result<Option<(K::Value, V::Value)>, D::Error>
+            where
+                K: DeserializeSeed<'de>,
+                V: DeserializeSeed<'de>,
+            {
+                self.0.next_entry_seed($wrapper(kseed), $wrapper(vseed))
+            }
             fn size_hint(&self) -> Option<usize> {
                 self.0.size_hint()
             }

serde_test/src/de.rs

@@ -168,14 +168,42 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
                         self.next_token();
                         visitor.visit_str(variant)
                     }
+                    (Token::BorrowedStr(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_borrowed_str(variant)
+                    }
+                    (Token::String(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_string(variant.to_string())
+                    }
                     (Token::Bytes(variant), Token::Unit) => {
                         self.next_token();
                         visitor.visit_bytes(variant)
                     }
+                    (Token::BorrowedBytes(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_borrowed_bytes(variant)
+                    }
+                    (Token::ByteBuf(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_byte_buf(variant.to_vec())
+                    }
+                    (Token::U8(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_u8(variant)
+                    }
+                    (Token::U16(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_u16(variant)
+                    }
                     (Token::U32(variant), Token::Unit) => {
                         self.next_token();
                         visitor.visit_u32(variant)
                     }
+                    (Token::U64(variant), Token::Unit) => {
+                        self.next_token();
+                        visitor.visit_u64(variant)
+                    }
                     (variant, Token::Unit) => unexpected!(variant),
                     (variant, _) => {
                         visitor.visit_map(EnumMapVisitor::new(self, variant, EnumFormat::Any))
@@ -250,9 +278,7 @@ impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
             {
                 visitor.visit_enum(DeserializerEnumVisitor { de: self })
             }
-            _ => {
-                unexpected!(self.next_token());
-            }
+            _ => self.deserialize_any(visitor),
         }
     }
 

serde_test/src/lib.rs

@@ -144,7 +144,7 @@
 //! # }
 //! ```
 
-#![doc(html_root_url = "https://docs.rs/serde_test/1.0.121")]
+#![doc(html_root_url = "https://docs.rs/serde_test/1.0.128")]
 #![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
 #![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
 // Ignored clippy lints
@@ -153,11 +153,14 @@
 #![cfg_attr(
     feature = "cargo-clippy",
     allow(
+        cloned_instead_of_copied,
         empty_line_after_outer_attr,
         missing_docs_in_private_items,
+        missing_panics_doc,
         module_name_repetitions,
         must_use_candidate,
         redundant_field_names,
+        too_many_lines,
         use_debug,
         use_self
     )

serde_test/src/ser.rs

@@ -32,18 +32,18 @@ impl<'a> Serializer<'a> {
 }
 
 macro_rules! assert_next_token {
-    ($ser:expr, $expected:ident) => {
-        assert_next_token!($ser, stringify!($expected), Token::$expected, true);
-    };
-    ($ser:expr, $expected:ident($v:expr)) => {
+    ($ser:expr, $actual:ident) => {{
+        assert_next_token!($ser, stringify!($actual), Token::$actual, true);
+    }};
+    ($ser:expr, $actual:ident($v:expr)) => {{
         assert_next_token!(
             $ser,
-            format_args!(concat!(stringify!($expected), "({:?})"), $v),
-            Token::$expected(v),
+            format_args!(concat!(stringify!($actual), "({:?})"), $v),
+            Token::$actual(v),
             v == $v
         );
-    };
-    ($ser:expr, $expected:ident { $($k:ident),* }) => {
+    }};
+    ($ser:expr, $actual:ident { $($k:ident),* }) => {{
         let compare = ($($k,)*);
         let field_format = || {
             use std::fmt::Write;
@@ -55,21 +55,21 @@ macro_rules! assert_next_token {
         };
         assert_next_token!(
             $ser,
-            format_args!(concat!(stringify!($expected), " {{ {}}}"), field_format()),
-            Token::$expected { $($k),* },
+            format_args!(concat!(stringify!($actual), " {{ {}}}"), field_format()),
+            Token::$actual { $($k),* },
             ($($k,)*) == compare
         );
-    };
-    ($ser:expr, $expected:expr, $pat:pat, $guard:expr) => {
+    }};
+    ($ser:expr, $actual:expr, $pat:pat, $guard:expr) => {
         match $ser.next_token() {
             Some($pat) if $guard => {}
-            Some(other) => {
+            Some(expected) => {
                 panic!("expected Token::{} but serialized as {}",
-                       $expected, other);
+                       expected, $actual);
             }
             None => {
-                panic!("expected Token::{} after end of serialized tokens",
-                       $expected);
+                panic!("expected end of tokens, but {} was serialized",
+                       $actual);
             }
         }
     };

test_suite/tests/expand/de_enum.expanded.rs

@@ -10,7 +10,7 @@ enum DeEnum<B, C, D> {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<B, C, D> _serde::Serialize for DeEnum<B, C, D>
@@ -265,7 +265,7 @@ const _: () = {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de, B, C, D> _serde::Deserialize<'de> for DeEnum<B, C, D>
@@ -573,12 +573,7 @@ const _: () = {
                                         1u64 => _serde::__private::Ok(__Field::__field1),
                                         2u64 => _serde::__private::Ok(__Field::__field2),
                                         3u64 => _serde::__private::Ok(__Field::__field3),
-                                        _ => _serde::__private::Err(
-                                            _serde::de::Error::invalid_value(
-                                                _serde::de::Unexpected::Unsigned(__value),
-                                                &"field index 0 <= i < 4",
-                                            ),
-                                        ),
+                                        _ => _serde::__private::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(
@@ -1081,12 +1076,7 @@ const _: () = {
                                         1u64 => _serde::__private::Ok(__Field::__field1),
                                         2u64 => _serde::__private::Ok(__Field::__field2),
                                         3u64 => _serde::__private::Ok(__Field::__field3),
-                                        _ => _serde::__private::Err(
-                                            _serde::de::Error::invalid_value(
-                                                _serde::de::Unexpected::Unsigned(__value),
-                                                &"field index 0 <= i < 4",
-                                            ),
-                                        ),
+                                        _ => _serde::__private::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(

test_suite/tests/expand/default_ty_param.expanded.rs

@@ -11,7 +11,7 @@ struct DefaultTyParam<T: AssociatedType<X = i32> = i32> {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<T: AssociatedType<X = i32>> _serde::Serialize for DefaultTyParam<T> {
@@ -49,7 +49,7 @@ const _: () = {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de, T: AssociatedType<X = i32>> _serde::Deserialize<'de> for DefaultTyParam<T> {
@@ -77,10 +77,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::__private::Ok(__Field::__field0),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(
@@ -260,10 +257,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::__private::Ok(__Field::__field0),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(

test_suite/tests/expand/generic_enum.expanded.rs

@@ -8,7 +8,7 @@ pub enum GenericEnum<T, U> {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<T, U> _serde::Serialize for GenericEnum<T, U>
@@ -114,7 +114,7 @@ const _: () = {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de, T, U> _serde::Deserialize<'de> for GenericEnum<T, U>
@@ -357,12 +357,7 @@ const _: () = {
                                     match __value {
                                         0u64 => _serde::__private::Ok(__Field::__field0),
                                         1u64 => _serde::__private::Ok(__Field::__field1),
-                                        _ => _serde::__private::Err(
-                                            _serde::de::Error::invalid_value(
-                                                _serde::de::Unexpected::Unsigned(__value),
-                                                &"field index 0 <= i < 2",
-                                            ),
-                                        ),
+                                        _ => _serde::__private::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(

test_suite/tests/expand/generic_struct.expanded.rs

@@ -5,7 +5,7 @@ pub struct GenericStruct<T> {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<T> _serde::Serialize for GenericStruct<T>
@@ -42,7 +42,7 @@ const _: () = {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de, T> _serde::Deserialize<'de> for GenericStruct<T>
@@ -73,10 +73,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::__private::Ok(__Field::__field0),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(
@@ -256,10 +253,7 @@ const _: () = {
                 {
                     match __value {
                         0u64 => _serde::__private::Ok(__Field::__field0),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 1",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(
@@ -416,7 +410,7 @@ pub struct GenericNewTypeStruct<T>(T);
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<T> _serde::Serialize for GenericNewTypeStruct<T>
@@ -441,7 +435,7 @@ const _: () = {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de, T> _serde::Deserialize<'de> for GenericNewTypeStruct<T>

test_suite/tests/expand/generic_tuple_struct.expanded.rs

@@ -3,7 +3,7 @@ pub struct GenericTupleStruct<T, U>(T, U);
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de, T, U> _serde::Deserialize<'de> for GenericTupleStruct<T, U>

test_suite/tests/expand/lifetimes.expanded.rs

@@ -8,7 +8,7 @@ enum Lifetimes<'a> {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'a> _serde::Serialize for Lifetimes<'a> {
@@ -95,7 +95,7 @@ const _: () = {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de, 'a> _serde::Deserialize<'de> for Lifetimes<'a> {
@@ -244,12 +244,7 @@ const _: () = {
                                 {
                                     match __value {
                                         0u64 => _serde::__private::Ok(__Field::__field0),
-                                        _ => _serde::__private::Err(
-                                            _serde::de::Error::invalid_value(
-                                                _serde::de::Unexpected::Unsigned(__value),
-                                                &"field index 0 <= i < 1",
-                                            ),
-                                        ),
+                                        _ => _serde::__private::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(
@@ -433,12 +428,7 @@ const _: () = {
                                 {
                                     match __value {
                                         0u64 => _serde::__private::Ok(__Field::__field0),
-                                        _ => _serde::__private::Err(
-                                            _serde::de::Error::invalid_value(
-                                                _serde::de::Unexpected::Unsigned(__value),
-                                                &"field index 0 <= i < 1",
-                                            ),
-                                        ),
+                                        _ => _serde::__private::Ok(__Field::__ignore),
                                     }
                                 }
                                 fn visit_str<__E>(

test_suite/tests/expand/named_map.expanded.rs

@@ -7,7 +7,7 @@ struct SerNamedMap<'a, 'b, A: 'a, B: 'b, C> {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'a, 'b, A: 'a, B: 'b, C> _serde::Serialize for SerNamedMap<'a, 'b, A, B, C>
@@ -63,7 +63,7 @@ struct DeNamedMap<A, B, C> {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de, A, B, C> _serde::Deserialize<'de> for DeNamedMap<A, B, C>
@@ -100,10 +100,7 @@ const _: () = {
                         0u64 => _serde::__private::Ok(__Field::__field0),
                         1u64 => _serde::__private::Ok(__Field::__field1),
                         2u64 => _serde::__private::Ok(__Field::__field2),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 3",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(
@@ -387,10 +384,7 @@ const _: () = {
                         0u64 => _serde::__private::Ok(__Field::__field0),
                         1u64 => _serde::__private::Ok(__Field::__field1),
                         2u64 => _serde::__private::Ok(__Field::__field2),
-                        _ => _serde::__private::Err(_serde::de::Error::invalid_value(
-                            _serde::de::Unexpected::Unsigned(__value),
-                            &"field index 0 <= i < 3",
-                        )),
+                        _ => _serde::__private::Ok(__Field::__ignore),
                     }
                 }
                 fn visit_str<__E>(

test_suite/tests/expand/named_tuple.expanded.rs

@@ -3,7 +3,7 @@ struct SerNamedTuple<'a, 'b, A: 'a, B: 'b, C>(&'a A, &'b mut B, C);
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'a, 'b, A: 'a, B: 'b, C> _serde::Serialize for SerNamedTuple<'a, 'b, A, B, C>
@@ -55,7 +55,7 @@ struct DeNamedTuple<A, B, C>(A, B, C);
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de, A, B, C> _serde::Deserialize<'de> for DeNamedTuple<A, B, C>

test_suite/tests/expand/named_unit.expanded.rs

@@ -3,7 +3,7 @@ struct NamedUnit;
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl _serde::Serialize for NamedUnit {
@@ -21,7 +21,7 @@ const _: () = {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de> _serde::Deserialize<'de> for NamedUnit {

test_suite/tests/expand/ser_enum.expanded.rs

@@ -13,7 +13,7 @@ where
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'a, B: 'a, C: 'a, D> _serde::Serialize for SerEnum<'a, B, C, D>

test_suite/tests/expand/void.expanded.rs

@@ -3,7 +3,7 @@ enum Void {}
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl _serde::Serialize for Void {
@@ -21,7 +21,7 @@ const _: () = {
 #[doc(hidden)]
 #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
 const _: () = {
-    #[allow(rust_2018_idioms, clippy::useless_attribute)]
+    #[allow(unused_extern_crates, clippy::useless_attribute)]
     extern crate serde as _serde;
     #[automatically_derived]
     impl<'de> _serde::Deserialize<'de> for Void {

test_suite/tests/test_annotations.rs

@@ -1,6 +1,8 @@
 #![allow(
     clippy::cast_lossless,
     clippy::from_over_into,
+    // Clippy bug: https://github.com/rust-lang/rust-clippy/issues/7422
+    clippy::nonstandard_macro_braces,
     clippy::trivially_copy_pass_by_ref
 )]
 
@@ -2637,3 +2639,171 @@ fn test_flatten_any_after_flatten_struct() {
         ],
     );
 }
+
+#[test]
+fn test_expecting_message() {
+    #[derive(Deserialize, PartialEq, Debug)]
+    #[serde(expecting = "something strange...")]
+    struct Unit;
+
+    #[derive(Deserialize)]
+    #[serde(expecting = "something strange...")]
+    struct Newtype(bool);
+
+    #[derive(Deserialize)]
+    #[serde(expecting = "something strange...")]
+    struct Tuple(u32, bool);
+
+    #[derive(Deserialize)]
+    #[serde(expecting = "something strange...")]
+    struct Struct {
+        question: String,
+        answer: u32,
+    }
+
+    assert_de_tokens_error::<Unit>(
+        &[Token::Str("Unit")],
+        r#"invalid type: string "Unit", expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<Newtype>(
+        &[Token::Str("Newtype")],
+        r#"invalid type: string "Newtype", expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<Tuple>(
+        &[Token::Str("Tuple")],
+        r#"invalid type: string "Tuple", expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<Struct>(
+        &[Token::Str("Struct")],
+        r#"invalid type: string "Struct", expected something strange..."#,
+    );
+}
+
+#[test]
+fn test_expecting_message_externally_tagged_enum() {
+    #[derive(Deserialize)]
+    #[serde(expecting = "something strange...")]
+    enum Enum {
+        ExternallyTagged,
+    }
+
+    assert_de_tokens_error::<Enum>(
+        &[Token::Str("ExternallyTagged")],
+        r#"invalid type: string "ExternallyTagged", expected something strange..."#,
+    );
+
+    // Check that #[serde(expecting = "...")] doesn't affect variant identifier error message
+    assert_de_tokens_error::<Enum>(
+        &[Token::Enum { name: "Enum" }, Token::Unit],
+        r#"invalid type: unit value, expected variant identifier"#,
+    );
+}
+
+#[test]
+fn test_expecting_message_internally_tagged_enum() {
+    #[derive(Deserialize)]
+    #[serde(tag = "tag")]
+    #[serde(expecting = "something strange...")]
+    enum Enum {
+        InternallyTagged,
+    }
+
+    assert_de_tokens_error::<Enum>(
+        &[Token::Str("InternallyTagged")],
+        r#"invalid type: string "InternallyTagged", expected something strange..."#,
+    );
+
+    // Check that #[serde(expecting = "...")] doesn't affect variant identifier error message
+    assert_de_tokens_error::<Enum>(
+        &[Token::Map { len: None }, Token::Str("tag"), Token::Unit],
+        r#"invalid type: unit value, expected variant identifier"#,
+    );
+}
+
+#[test]
+fn test_expecting_message_adjacently_tagged_enum() {
+    #[derive(Deserialize)]
+    #[serde(tag = "tag", content = "content")]
+    #[serde(expecting = "something strange...")]
+    enum Enum {
+        AdjacentlyTagged,
+    }
+
+    assert_de_tokens_error::<Enum>(
+        &[Token::Str("AdjacentlyTagged")],
+        r#"invalid type: string "AdjacentlyTagged", expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<Enum>(
+        &[Token::Map { len: None }, Token::Unit],
+        r#"invalid type: unit value, expected "tag", "content", or other ignored fields"#,
+    );
+
+    // Check that #[serde(expecting = "...")] doesn't affect variant identifier error message
+    assert_de_tokens_error::<Enum>(
+        &[Token::Map { len: None }, Token::Str("tag"), Token::Unit],
+        r#"invalid type: unit value, expected variant identifier"#,
+    );
+}
+
+#[test]
+fn test_expecting_message_untagged_tagged_enum() {
+    #[derive(Deserialize)]
+    #[serde(untagged)]
+    #[serde(expecting = "something strange...")]
+    enum Enum {
+        Untagged,
+    }
+
+    assert_de_tokens_error::<Enum>(&[Token::Str("Untagged")], r#"something strange..."#);
+}
+
+#[test]
+fn test_expecting_message_identifier_enum() {
+    #[derive(Deserialize)]
+    #[serde(field_identifier)]
+    #[serde(expecting = "something strange...")]
+    enum FieldEnum {
+        Field,
+    }
+
+    #[derive(Deserialize)]
+    #[serde(variant_identifier)]
+    #[serde(expecting = "something strange...")]
+    enum VariantEnum {
+        Variant,
+    }
+
+    assert_de_tokens_error::<FieldEnum>(
+        &[Token::Unit],
+        r#"invalid type: unit value, expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<FieldEnum>(
+        &[
+            Token::Enum { name: "FieldEnum" },
+            Token::Str("Unknown"),
+            Token::None,
+        ],
+        r#"invalid type: map, expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<VariantEnum>(
+        &[Token::Unit],
+        r#"invalid type: unit value, expected something strange..."#,
+    );
+
+    assert_de_tokens_error::<VariantEnum>(
+        &[
+            Token::Enum {
+                name: "VariantEnum",
+            },
+            Token::Str("Unknown"),
+            Token::None,
+        ],
+        r#"invalid type: map, expected something strange..."#,
+    );
+}

test_suite/tests/test_de.rs

@@ -15,7 +15,7 @@ use std::sync::atomic::{
     AtomicUsize, Ordering,
 };
 use std::sync::{Arc, Weak as ArcWeak};
-use std::time::{Duration, UNIX_EPOCH};
+use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
 #[cfg(target_arch = "x86_64")]
 use std::sync::atomic::{AtomicI64, AtomicU64};
@@ -192,8 +192,12 @@ macro_rules! declare_tests {
 }
 
 macro_rules! declare_error_tests {
-    ($($name:ident<$target:ty> { $tokens:expr, $expected:expr, })+) => {
+    ($(
+        $(#[$cfg:meta])*
+        $name:ident<$target:ty> { $tokens:expr, $expected:expr, }
+    )+) => {
         $(
+            $(#[$cfg])*
             #[test]
             fn $name() {
                 assert_de_tokens_error::<$target>($tokens, $expected);
@@ -622,6 +626,24 @@ declare_tests! {
                 Token::I32(2),
             Token::MapEnd,
         ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::U8(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U16(0),
+                Token::I32(1),
+
+                Token::U16(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Map { len: Some(3) },
                 Token::U32(0),
@@ -631,6 +653,34 @@ declare_tests! {
                 Token::I32(2),
             Token::MapEnd,
         ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U64(0),
+                Token::I32(1),
+
+                Token::U64(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        // Mixed key types
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::U64(1),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::Str("b"),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Struct { name: "Struct", len: 2 },
                 Token::Str("a"),
@@ -647,6 +697,46 @@ declare_tests! {
             Token::SeqEnd,
         ],
     }
+    test_struct_borrowed_keys {
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::BorrowedStr("a"),
+                Token::I32(1),
+
+                Token::BorrowedStr("b"),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Struct { name: "Struct", len: 2 },
+                Token::BorrowedStr("a"),
+                Token::I32(1),
+
+                Token::BorrowedStr("b"),
+                Token::I32(2),
+            Token::StructEnd,
+        ],
+    }
+    test_struct_owned_keys {
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::String("a"),
+                Token::I32(1),
+
+                Token::String("b"),
+                Token::I32(2),
+            Token::MapEnd,
+        ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Struct { name: "Struct", len: 2 },
+                Token::String("a"),
+                Token::I32(1),
+
+                Token::String("b"),
+                Token::I32(2),
+            Token::StructEnd,
+        ],
+    }
     test_struct_with_skip {
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Map { len: Some(3) },
@@ -663,6 +753,21 @@ declare_tests! {
                 Token::I32(4),
             Token::MapEnd,
         ],
+        Struct { a: 1, b: 2, c: 0 } => &[
+            Token::Map { len: Some(3) },
+                Token::U8(0),
+                Token::I32(1),
+
+                Token::U16(1),
+                Token::I32(2),
+
+                Token::U32(2),
+                Token::I32(3),
+
+                Token::U64(3),
+                Token::I32(4),
+            Token::MapEnd,
+        ],
         Struct { a: 1, b: 2, c: 0 } => &[
             Token::Struct { name: "Struct", len: 2 },
                 Token::Str("a"),
@@ -780,6 +885,26 @@ declare_tests! {
             Token::Str("Unit"),
             Token::Unit,
         ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U8(0),
+            Token::Unit,
+        ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U16(0),
+            Token::Unit,
+        ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U32(0),
+            Token::Unit,
+        ],
+        EnumOther::Unit => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U64(0),
+            Token::Unit,
+        ],
     }
     test_enum_other {
         EnumOther::Other => &[
@@ -787,6 +912,26 @@ declare_tests! {
             Token::Str("Foo"),
             Token::Unit,
         ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U8(42),
+            Token::Unit,
+        ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U16(42),
+            Token::Unit,
+        ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U32(42),
+            Token::Unit,
+        ],
+        EnumOther::Other => &[
+            Token::Enum { name: "EnumOther" },
+            Token::U64(42),
+            Token::Unit,
+        ],
     }
     test_box {
         Box::new(0i32) => &[Token::I32(0)],
@@ -1473,4 +1618,35 @@ declare_error_tests! {
         ],
         "overflow deserializing Duration",
     }
+    test_systemtime_overflow_seq<SystemTime> {
+        &[
+            Token::Seq { len: Some(2) },
+                Token::U64(u64::max_value()),
+                Token::U32(1_000_000_000),
+            Token::SeqEnd,
+        ],
+        "overflow deserializing SystemTime epoch offset",
+    }
+    test_systemtime_overflow_struct<SystemTime> {
+        &[
+            Token::Struct { name: "SystemTime", len: 2 },
+                Token::Str("secs_since_epoch"),
+                Token::U64(u64::max_value()),
+
+                Token::Str("nanos_since_epoch"),
+                Token::U32(1_000_000_000),
+            Token::StructEnd,
+        ],
+        "overflow deserializing SystemTime epoch offset",
+    }
+    #[cfg(systemtime_checked_add)]
+    test_systemtime_overflow<SystemTime> {
+        &[
+            Token::Seq { len: Some(2) },
+                Token::U64(u64::max_value()),
+                Token::U32(0),
+            Token::SeqEnd,
+        ],
+        "overflow deserializing SystemTime",
+    }
 }

test_suite/tests/test_gen.rs

@@ -3,10 +3,12 @@
 // types involved.
 
 #![deny(warnings)]
-#![cfg_attr(feature = "unstable", feature(non_ascii_idents))]
 #![allow(
     unknown_lints,
     mixed_script_confusables,
+    // Clippy bug: https://github.com/rust-lang/rust-clippy/issues/7422
+    clippy::nonstandard_macro_braces,
+    clippy::ptr_arg,
     clippy::trivially_copy_pass_by_ref
 )]
 
@@ -266,7 +268,6 @@ fn test_gen() {
     }
     assert::<EmptyEnumVariant>();
 
-    #[cfg(feature = "unstable")]
     #[derive(Serialize, Deserialize)]
     struct NonAsciiIdents {
         σ: f64,
@@ -642,7 +643,7 @@ fn test_gen() {
     assert::<SkippedVariant<X>>();
 
     #[derive(Deserialize)]
-    struct ImpliciltyBorrowedOption<'a> {
+    struct ImplicitlyBorrowedOption<'a> {
         option: std::option::Option<&'a str>,
     }
 
@@ -723,6 +724,24 @@ fn test_gen() {
     }
 
     deriving!(&'a str);
+
+    macro_rules! mac {
+        ($($tt:tt)*) => {
+            $($tt)*
+        };
+    }
+
+    #[derive(Deserialize)]
+    struct BorrowLifetimeInsideMacro<'a> {
+        #[serde(borrow = "'a")]
+        f: mac!(Cow<'a, str>),
+    }
+
+    #[derive(Serialize)]
+    struct Struct {
+        #[serde(serialize_with = "vec_first_element")]
+        vec: Vec<Self>,
+    }
 }
 
 //////////////////////////////////////////////////////////////////////////
@@ -796,3 +815,11 @@ where
 pub fn is_zero(n: &u8) -> bool {
     *n == 0
 }
+
+fn vec_first_element<T, S>(vec: &Vec<T>, serializer: S) -> StdResult<S::Ok, S::Error>
+where
+    T: Serialize,
+    S: Serializer,
+{
+    vec.first().serialize(serializer)
+}

test_suite/tests/test_identifier.rs

@@ -1,3 +1,4 @@
+//! Tests for `#[serde(field_identifier)]` and `#[serde(variant_identifier)]`
 use serde::Deserialize;
 use serde_test::{assert_de_tokens, Token};
 
@@ -27,6 +28,10 @@ fn test_field_identifier() {
         Bbb,
     }
 
+    assert_de_tokens(&F::Aaa, &[Token::U8(0)]);
+    assert_de_tokens(&F::Aaa, &[Token::U16(0)]);
+    assert_de_tokens(&F::Aaa, &[Token::U32(0)]);
+    assert_de_tokens(&F::Aaa, &[Token::U64(0)]);
     assert_de_tokens(&F::Aaa, &[Token::Str("aaa")]);
     assert_de_tokens(&F::Aaa, &[Token::Bytes(b"aaa")]);
 }
@@ -42,6 +47,10 @@ fn test_unit_fallthrough() {
         Other,
     }
 
+    assert_de_tokens(&F::Other, &[Token::U8(42)]);
+    assert_de_tokens(&F::Other, &[Token::U16(42)]);
+    assert_de_tokens(&F::Other, &[Token::U32(42)]);
+    assert_de_tokens(&F::Other, &[Token::U64(42)]);
     assert_de_tokens(&F::Other, &[Token::Str("x")]);
 }
 
@@ -68,5 +77,9 @@ fn test_newtype_fallthrough_generic() {
         Other(T),
     }
 
+    assert_de_tokens(&F::Other(42u8), &[Token::U8(42)]);
+    assert_de_tokens(&F::Other(42u16), &[Token::U16(42)]);
+    assert_de_tokens(&F::Other(42u32), &[Token::U32(42)]);
+    assert_de_tokens(&F::Other(42u64), &[Token::U64(42)]);
     assert_de_tokens(&F::Other("x".to_owned()), &[Token::Str("x")]);
 }

test_suite/tests/test_macros.rs

@@ -994,6 +994,28 @@ fn test_internally_tagged_struct_variant_containing_unit_variant() {
             Token::StructEnd,
         ],
     );
+
+    assert_de_tokens(
+        &Message::Log { level: Level::Info },
+        &[
+            Token::Map { len: Some(2) },
+            Token::Str("action"),
+            Token::Str("Log"),
+            Token::Str("level"),
+            Token::BorrowedStr("Info"),
+            Token::MapEnd,
+        ],
+    );
+
+    assert_de_tokens(
+        &Message::Log { level: Level::Info },
+        &[
+            Token::Seq { len: Some(2) },
+            Token::Str("Log"),
+            Token::BorrowedStr("Info"),
+            Token::SeqEnd,
+        ],
+    );
 }
 
 #[test]
@@ -1877,9 +1899,31 @@ fn test_internally_tagged_newtype_variant_containing_unit_struct() {
             Token::MapEnd,
         ],
     );
+
+    assert_de_tokens(
+        &Message::Info(Info),
+        &[
+            Token::Struct {
+                name: "Message",
+                len: 1,
+            },
+            Token::Str("topic"),
+            Token::Str("Info"),
+            Token::StructEnd,
+        ],
+    );
+
+    assert_de_tokens(
+        &Message::Info(Info),
+        &[
+            Token::Seq { len: Some(1) },
+            Token::Str("Info"),
+            Token::SeqEnd,
+        ],
+    );
 }
 
-#[deny(safe_packed_borrows)]
+#[deny(unaligned_references)]
 #[test]
 fn test_packed_struct_can_derive_serialize() {
     #[derive(Copy, Clone, Serialize)]

test_suite/tests/test_self.rs

@@ -0,0 +1,86 @@
+use serde::{Deserialize, Serialize};
+
+#[test]
+fn test_self() {
+    pub trait Trait {
+        type Assoc;
+    }
+
+    #[derive(Deserialize, Serialize)]
+    pub struct Generics<T: Trait<Assoc = Self>>
+    where
+        Self: Trait<Assoc = Self>,
+        <Self as Trait>::Assoc: Sized,
+    {
+        _f: T,
+    }
+
+    impl<T: Trait<Assoc = Self>> Trait for Generics<T> {
+        type Assoc = Self;
+    }
+
+    #[derive(Deserialize, Serialize)]
+    pub struct Struct {
+        _f1: Box<Self>,
+        _f2: Box<<Self as Trait>::Assoc>,
+        _f4: [(); Self::ASSOC],
+        _f5: [(); Self::assoc()],
+    }
+
+    impl Struct {
+        const ASSOC: usize = 1;
+        const fn assoc() -> usize {
+            0
+        }
+    }
+
+    impl Trait for Struct {
+        type Assoc = Self;
+    }
+
+    #[derive(Deserialize, Serialize)]
+    struct Tuple(
+        Box<Self>,
+        Box<<Self as Trait>::Assoc>,
+        [(); Self::ASSOC],
+        [(); Self::assoc()],
+    );
+
+    impl Tuple {
+        const ASSOC: usize = 1;
+        const fn assoc() -> usize {
+            0
+        }
+    }
+
+    impl Trait for Tuple {
+        type Assoc = Self;
+    }
+
+    #[derive(Deserialize, Serialize)]
+    enum Enum {
+        Struct {
+            _f1: Box<Self>,
+            _f2: Box<<Self as Trait>::Assoc>,
+            _f4: [(); Self::ASSOC],
+            _f5: [(); Self::assoc()],
+        },
+        Tuple(
+            Box<Self>,
+            Box<<Self as Trait>::Assoc>,
+            [(); Self::ASSOC],
+            [(); Self::assoc()],
+        ),
+    }
+
+    impl Enum {
+        const ASSOC: usize = 1;
+        const fn assoc() -> usize {
+            0
+        }
+    }
+
+    impl Trait for Enum {
+        type Assoc = Self;
+    }
+}

test_suite/tests/ui/remote/wrong_de.stderr

@@ -7,4 +7,4 @@ error[E0308]: mismatched types
   |          expected `u16`, found `u8`
   |          help: you can convert a `u8` to a `u16`: `Deserialize.into()`
   |
-  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
+  = note: this error originates in the derive macro `Deserialize` (in Nightly builds, run with -Z macro-backtrace for more info)

test_suite/tests/ui/remote/wrong_getter.stderr

@@ -6,4 +6,4 @@ error[E0308]: mismatched types
    |
    = note: expected reference `&u8`
               found reference `&u16`
-   = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the derive macro `Serialize` (in Nightly builds, run with -Z macro-backtrace for more info)

test_suite/tests/ui/remote/wrong_ser.stderr

@@ -6,4 +6,4 @@ error[E0308]: mismatched types
   |
   = note: expected reference `&u8`
              found reference `&u16`
-  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
+  = note: this error originates in the derive macro `Serialize` (in Nightly builds, run with -Z macro-backtrace for more info)

test_suite/tests/ui/rename/container_unknown_rename_rule.stderr

@@ -1,4 +1,4 @@
-error: unknown rename rule for #[serde(rename_all = "abc")]
+error: unknown rename rule `rename_all = "abc"`, expected one of "lowercase", "UPPERCASE", "PascalCase", "camelCase", "snake_case", "SCREAMING_SNAKE_CASE", "kebab-case", "SCREAMING-KEBAB-CASE"
  --> $DIR/container_unknown_rename_rule.rs:4:22
   |
 4 | #[serde(rename_all = "abc")]

test_suite/tests/ui/rename/variant_unknown_rename_rule.stderr

@@ -1,4 +1,4 @@
-error: unknown rename rule for #[serde(rename_all = "abc")]
+error: unknown rename rule `rename_all = "abc"`, expected one of "lowercase", "UPPERCASE", "PascalCase", "camelCase", "snake_case", "SCREAMING_SNAKE_CASE", "kebab-case", "SCREAMING-KEBAB-CASE"
  --> $DIR/variant_unknown_rename_rule.rs:5:26
   |
 5 |     #[serde(rename_all = "abc")]

test_suite/tests/ui/struct-representation/internally-tagged-unit.stderr

@@ -4,4 +4,4 @@ error: #[serde(tag = "...")] can only be used on enums and structs with named fi
 3 | #[derive(Serialize)]
   |          ^^^^^^^^^
   |
-  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
+  = note: this error originates in the derive macro `Serialize` (in Nightly builds, run with -Z macro-backtrace for more info)